How To Check If Japanese Land Is In A Landslide Hazard Zone (土砂災害警戒区域)

The two zones, and what "sediment disaster" means in the statute

Article 2 defines 土砂災害 as harm to life or limb caused by one of four natural phenomena: the collapse of a steep slope (急傾斜地の崩壊, where the statute itself defines a steep slope as land inclined at 30 degrees or more), a debris flow (土石流), a landslip (地滑り), or ponding behind a river channel blocked by sediment (河道閉塞による湛水). The first three are grouped in the Act as 急傾斜地の崩壊等.

The fourth one drops out immediately. Article 7, paragraph 1 excludes river-blockage ponding from the meaning of 土砂災害 for the whole of the chapters that create the two zones, so both the yellow and the red zone are designated for slope collapse, debris flow or landslip only, and the designation states which of the three it was made for. Article 7, paragraph 2 requires the designation to be made separately for each cause, naming the area and the type of natural phenomenon.

• 土砂災害警戒区域 (yellow). Article 7: land where, if a sediment disaster occurred, there is a risk of harm to the life or limb of residents, and where a warning and evacuation system should particularly be put in place. The governor must hear the views of the relevant municipal mayor first, then publish a notice and send the municipality the documents and maps recording it.
• 土砂災害特別警戒区域 (red). Article 9: the part of a yellow zone where, if a sediment disaster occurred, buildings would be damaged and residents would face a marked risk of harm to life or limb, and where certain development should be restricted and the structure of buildings containing habitable rooms should be regulated. A red zone is by definition inside a yellow zone, which is why a red-zone parcel is also subject to everything in the yellow zone.

A red-zone designation takes legal effect on publication of the notice (Article 9, paragraph 6), and the designation itself fixes numbers your architect will need: Article 9, paragraph 2 and Article 4 of the Enforcement Order require it to record the type of phenomenon, the maximum force assumed to act on a building, and the assumed height of the sediment or debris flow, zone by zone.

How common this is, and what the numbers do and do not count

The national designation figures, published by MLIT and current to 30 June 2026, break down by cause as follows.

• Steep slope collapse (急傾斜地の崩壊): 482,534 yellow zones, of which 459,201 are also red.
• Debris flow (土石流): 222,068 yellow zones, of which 162,085 are also red.
• Landslip (地滑り): 16,412 yellow zones, of which 1 is also red.
• Total: 721,014 yellow zones, of which 621,287 are also red.

Three things in those figures are worth absorbing before you look at a listing.

First, a yellow-zone designation is usually not the end of the story: 95 percent of steep-slope yellow zones are also red, and 73 percent of debris-flow yellow zones are. If a parcel is in a yellow zone, assume it may be in a red zone until the prefecture tells you otherwise.

Second, landslip is the exception that proves the rule. There are 16,412 landslip yellow zones in Japan and exactly one landslip red zone, in Toyama Prefecture. The red-zone test is a calculation about force on a building, and a slow-moving slide block rarely meets it.

Third, a zone is not a parcel. Each of those 721,014 entries is a mapped area around one slope, one stream or one slide block, and a single zone can cover many properties while a single property can sit in more than one. Do not read the figure as a count of affected homes.

The sweep is also essentially finished. MLIT has retired the older 土砂災害危険箇所 dataset (the legacy inventory of dangerous debris-flow streams, landslip locations and steep-slope sites surveyed from 1966 onwards), stating that the work of surveying and publishing such areas was taken over by the 土砂災害防止法 and that designation under it is now broadly complete nationwide. Designated yellow zones, 721,014, now account for almost all of the 726,539 zones recorded on the same sheet as surveyed and published. That matters for how you read a negative answer: twenty years ago an undesignated slope might simply have been unsurveyed, and today an undesignated slope is much more likely to have been looked at and not designated.

A negative answer is still only current, though, because the survey behind these designations repeats. Article 4, paragraph 1 requires each prefecture to carry out the 基礎調査 roughly every five years, looking at the landform, geology and rainfall of land at risk and at how that land is being used, and paragraph 2 requires the results to be notified to the municipality and published. Designations move with it in both directions: Shimane Prefecture's manual on the permit confirms that a later survey can turn a yellow zone into a red one, and that a red zone can cover land with no houses on it at all, because the test takes in land where development is foreseeable rather than only land already built on. Two more points from the same manual are worth knowing before a site visit. An engineered slope is not outside the Act: an artificial cut or fill counts if a natural collapse could occur on it. And no on-site marker is legally required, with the designation published by notice and drawings instead, so there may be nothing whatsoever to see on the ground. You cannot do this check by walking the site.

What the yellow zone restricts: for an ordinary house, nothing

This is the single most common misunderstanding, and it runs in both directions: buyers panic at a yellow-zone designation, and sellers wave it away as a formality. Neither is right.

A yellow-zone designation imposes no permit requirement, no building restriction and no structural standard on an ordinary owner. What it does is switch on duties for the municipality. Article 8 requires the municipal disaster management council to set out, in the municipal regional disaster management plan and for each zone, how sediment disaster information will be collected and transmitted, where the evacuation facilities and routes are, how evacuation drills will be run, which facilities used by people needing special care sit inside the zone, and what rescue arrangements apply. Article 8, paragraph 3 then requires the mayor to make those matters known to residents, by distributing printed material or taking other necessary measures. In practice that is the municipal 土砂災害ハザードマップ, and MLIT reports that of the 1,602 municipalities that have designated or plan to designate a yellow zone, approximately 100 percent publish one, with 96 percent of surveyed zones already shown on it, both figures current to the end of March 2026.

There is one real owner-side duty in the yellow zone, and it is narrow. Under Article 8-2, where a facility used by people needing special care (要配慮者利用施設, which the Act defines as social welfare facilities, schools, medical facilities and other facilities used mainly by people needing consideration in a disaster) has had its name and location written into the municipal plan under Article 8, paragraph 1, item 4, the owner or manager of that facility must prepare a plan for securing the smooth and rapid evacuation of its users, report it to the mayor, and conduct the drills and other measures the plan provides for. A mayor who finds no plan has been made may issue instructions, and may publicly name an owner who ignores them without just cause. If you are buying a care home, a clinic or a kindergarten rather than a house, read that article properly.

So the practical effect of a yellow zone on a residential buyer is informational: it tells you the prefecture has assessed this ground as capable of killing someone, it means a municipal hazard map almost certainly exists, and it triggers a disclosure duty on a licensed agent. It does not stop you building. Note the gap in that middle point, because it cuts the wrong way for a buyer: the municipality publishing a map is near universal, but 32,029 surveyed zones, about 4 percent, were not yet shown on one at the end of March 2026. A zone missing from the map layer is not evidence that no designation exists, which is why the prefecture's own designation records, and not the map, are the authoritative check.

What the red zone restricts: development for other people, not your own main home

The red zone does carry a permit regime, and its scope is narrower than almost every summary suggests.

Article 10, paragraph 1 requires the prefectural governor's prior permission for a 特定開発行為, which has two cumulative elements:

• a 開発行為 as defined in Article 4, paragraph 12 of the City Planning Act, meaning a change to the division, form or quality of land (土地の区画形質の変更) carried out mainly for the purpose of erecting buildings or constructing specified structures; and
• a planned building (予定建築物) whose use is a 制限用途.

Article 10, paragraph 2 defines 制限用途 through a double negative, and the result is this: the restricted uses are housing other than housing to be used as the developer's own residence (住宅（自己の居住の用に供するものを除く）), together with the welfare facilities, schools and medical facilities specified by Cabinet Order.

The own-residence carve-out is narrower than it sounds, and this is the point for anyone buying in Japan from abroad. Prefectural guidance on this permit reads 自己の居住の用 as the developer using the house as their own main base of life (生活の本拠). Shimane Prefecture's manual sets out what therefore falls outside it, and the list includes dormitories, company housing, housing a co-operative will transfer to its members, and expressly a holiday home (別荘), on the ground that a second home is not a main base of life. Shizuoka Prefecture gives the same shape from the other side, listing subdivided housing, apartment blocks and company housing as the restricted cases. So a holiday house in a red zone is a restricted use, and if building it involves a change to the division, form or quality of the land it needs the governor's permission. Shimane's manual also explains why the line is drawn there: carrying out development for other people's use inside a red zone amounts to helping or compelling others to approach a known danger, which is a different kind of responsibility from taking the risk yourself. Article 6 of the Enforcement Order specifies those: facilities for the elderly and for disabled adults and children, protective and child welfare facilities, maternal and child welfare facilities and similar; special-needs schools and kindergartens only, not ordinary schools; and hospitals, clinics and midwifery homes. Article 5 of the Order exempts emergency response works and development for temporary buildings.

Read together, that means building a house you will live in as your own main home is not a 特定開発行為 at all, and needs no Article 10 permission. Building houses to sell or to rent does. Building a care home or a clinic does. And if there is no change to the division, form or quality of the land, for example because you are putting a house on an existing building plot, there is no 開発行為 either, so Article 10 does not bite even on rental housing.

Where the permit is required, Article 19 bars construction of a restricted-use building on the land in the permitted development area, limited to the part inside the red zone, until the completion of works has been publicly notified, and the penalties are not nominal. Article 38 punishes carrying out a 特定開発行為 without permission, building in breach of Article 19, or disobeying a supervisory order under Article 21, paragraph 1, with imprisonment of up to one year or a fine of up to ¥500,000. Article 42 imposes a civil fine (過料) of up to ¥200,000 for failing to file, or filing falsely, the notification owed under Article 14, paragraph 1 by a person already carrying out works when the zone was designated.

The City Planning Act reinforces this from the other side. Article 33, paragraph 1, item 8 provides that for a development other than one carried out mainly to build a dwelling for the developer's own residence, the development area must not include land inside a 災害危険区域等, a list that expressly names the 土砂災害特別警戒区域, subject to a proviso where the circumstances of the area and its surroundings are found to raise no difficulty. It uses the same 自己の居住の用に供する住宅 wording, so the main-home reading above applies to it too, and it has a proviso, so do not treat either as an absolute bar.

What the red zone does to your own house anyway

Two things, and they are the ones that cost money.

A building confirmation can become compulsory where it otherwise would not be. Article 25 deems a building containing a habitable room (居室, as defined in Article 2, item 4 of the Building Standards Act) inside a red zone to be a building inside an area designated by the governor under Article 6, paragraph 1, item 3 of the Building Standards Act, and applies Articles 6 to 7-5, 18, 89, 91 and 93 of that Act to it, penalties included. The deeming is drafted to skip the cases that already need a confirmation: it excludes any part of a red zone that is itself an item 3 area, and excludes buildings caught by items 1 or 2. The effect matters most on rural land. Building confirmation normally reaches, under Article 6, paragraph 1, a special-use building over 200 square metres (item 1), any building of two or more storeys or over 200 square metres (item 2), and otherwise only buildings inside a city planning area, a quasi-city planning area, a quasi-scenic district or a governor-designated area (item 3). A single-storey house under 200 square metres on land outside any city planning area therefore escapes confirmation in the ordinary case.

Whether it escapes it in a red zone turns on how much of the site is inside the zone, and this is the detail to get right on a boundary parcel. Article 91, which Article 25 expressly switches on, provides that where a building site straddles the inside and outside of an area carrying restrictions under the Act, the provisions for the area containing the majority of the site (敷地の過半) apply to the whole building and site. Okinawa Prefecture's building guidance states the combined result plainly: a confirmation is required where a building with a habitable room is wholly or partly inside the red zone and the majority of the site is inside it. The ordinary exemption in Article 6, paragraph 2 for an addition, rebuild or relocation of 10 square metres or less outside a fire prevention district sits inside Article 6 and so is applied along with it.

The structural rule does not follow the majority of the site, and conflating the two is the mistake to avoid. The same prefectural guidance notes that even where no confirmation is required because most of the site lies outside the red zone, the structural regulation still applies if any part of the building is inside it.

When you build, the walls have to be engineered for the impact. Article 24 directs that the Cabinet Order under Article 20, paragraph 1 of the Building Standards Act set a structural strength standard for buildings with habitable rooms in red zones, and Article 80-3 of the Building Standards Act Enforcement Order does it. For the external walls and the parts of the building structurally essential to load bearing, up to the height of the sediment or debris flow fixed in the designation and limited to the parts where impact is assumed to act, the structure must use a method specified by the Minister as not failing under the assumed impact, calculated from the type of phenomenon, the maximum assumed force and the sediment height recorded in the designation. There is a proviso worth knowing before you price the work: the standard does not apply where a gate or wall at or above the sediment height, itself using a Minister-specified method of equivalent or greater strength, is positioned to block the assumed impact. A barrier can do the job instead of the house. The method itself is specified in a Ministry of Land, Infrastructure, Transport and Tourism notification (平成13年国土交通省告示第383号), which is what a designer works from.

This standard is a rule about building work, not a retrofit order on existing houses, and the distinction matters if you are buying a house that is already standing. Under Article 3, paragraph 2 of the Building Standards Act, a building already in existence when a provision comes into force or becomes applicable to it, and which does not comply, is simply outside that provision: it becomes 既存不適格 (existing nonconforming) rather than unlawful, so a red-zone designation made after the house was built does not by itself oblige the owner to engineer the walls. The protection is not permanent. Article 3, paragraph 3, item 3 withdraws it for an extension, rebuild, relocation, major repair or major alteration whose work begins after the provision applies, so the standard is what you meet when you build, extend or rebuild. MLIT runs a subsidy programme aimed at exactly these existing nonconforming red-zone buildings, which is a reasonable indication of how common the situation is.

That withdrawal is not the last word either, and this is where an owner planning limited work can badly overestimate the cost. Article 86-7, paragraph 1 provides that where an extension, rebuild, major repair or major alteration is carried out within the range set by Cabinet Order to a building that escapes Article 20 under Article 3, paragraph 2, then notwithstanding Article 3, paragraph 3, items 3 and 4, Article 20 still does not apply, and for an extension or rebuild only where the resulting structure meets the standards that Order sets. Because the red-zone wall standard is made under Article 20, paragraph 1, that relaxation reaches it.

The qualifying range is set separately for each kind of work, which is the part to get right before you price anything. For an extension or rebuild it is Article 137-2 of the Enforcement Order, with the structural standards that article sets. For a major repair or major alteration it is Article 137-12, paragraph 1, and the range there is generous: all such work that does not increase the building's structural danger. Relocation runs on its own track, under Article 86-7, paragraph 4 with Article 137-16 of the Order, and that one reaches the Building Standards Act provisions generally rather than Article 20 alone: a relocation within the same site qualifies, as does one the building authority finds unobjectionable on traffic, safety, fire, evacuation, sanitation and urban-environment grounds. So before pricing a project on the assumption that full red-zone compliance is unavoidable, ask the building authority which range your work falls in.

Beyond construction, Article 26 lets the governor recommend (勧告) that the owner, manager or occupier of a building with habitable rooms in a red zone relocate it or take other measures to prevent or reduce sediment disaster, where the risk of serious harm is judged high. It is a recommendation, not an order, and paragraph 2 obliges the governor to endeavour to arrange assistance such as brokering the acquisition of land where that is necessary. There is also a route out: Article 9, paragraph 8 provides that the governor shall release all or part of a red zone when the grounds for designation have ceased to exist, for example once sediment control works have been built. Unlike some Japanese land designations, this one is genuinely tied to the physical condition of the slope.

Four neighbouring designations that are not this one

Japanese slope regulation is a patchwork, and the names collide. There is a useful way to keep them apart, which Shimane Prefecture's manual draws out: the older designations below are mostly cause-side controls, aimed at the ground that might fail and at acts that could trigger a failure, while the 土砂災害防止法 zones describe the area that would be harmed if it did. Ask about each separately.

• 急傾斜地崩壊危険区域 under the Act on Prevention of Disasters Caused by Collapse of Steep Slopes (急傾斜地法). Article 3 lets the governor designate a steep slope liable to collapse that would endanger a substantial number of residents, plus adjoining land. Article 7 then requires the governor's permission for a list of acts: discharging or retaining water and other acts promoting infiltration, installing or altering facilities or structures other than slope-protection works, cutting, excavating or filling, felling trees and bamboo, skidding or dragging out timber, and extracting or stockpiling earth and stone. Article 2 of its Enforcement Order then exempts three different kinds of act, and only one of them is about size. It exempts a set of ordinary water uses outright (discharging or retaining water on a paddy field, discharging water for irrigation or from daily use, discharging into a drainage channel, and discharging into or storing water in a pond or other storage facility), removal cutting and the felling of fallen or dead trees and bamboo, small works near the slope with stated thresholds (below the toe, a cut or excavation of 50 centimetres or less kept at least 2 metres from the toe, or filling of 2 metres or less), and a long list of works already authorised under other statutes, from railways and mining to land improvement and quarrying. So do not assume an act needs consent just because it is not small: check the list. Anyone already carrying out a restricted act when the zone is designated must notify the governor within 14 days. This is a regime about earthworks and structures rather than about building use, MLIT states that the permission rules are implemented through prefectural ordinances, and the practical point for a buyer is that groundworks on such a parcel will usually need consent.
• 災害危険区域 under Article 39 of the Building Standards Act. A local authority (地方公共団体, which means either a prefecture or a municipality) may designate, by ordinance, areas of marked danger from tsunami, high tide, flooding and the like, and the same ordinance sets the restrictions, which may go as far as prohibiting residential buildings outright. This is the designation that can actually ban a house, and which body designates it varies: Osaka Prefecture, for example, uses its own prefectural building ordinance to define its 災害危険区域 as the 急傾斜地崩壊危険区域 plus other areas of marked steep-slope collapse danger designated by the governor, while some cities within it designate under a municipal ordinance instead. So it is a separate enquiry from the sediment-disaster zones, and you have to ask whichever body designates it locally.
• 宅地造成等工事規制区域 and 特定盛土等規制区域 under the Act on Regulation of Residential Land Development (盛土規制法), which regulate the earthworks themselves rather than the hazard, and which are the regime to ask about if the parcel has been cut or filled.
• 造成宅地防災区域 under Article 45 of that same Act, which is a separate item in the agent's disclosure list.

The disclosure duty, and the sale where nobody owes it

Whether a property sits in a yellow zone is an enumerated item in the important matters explanation (重要事項説明) that a licensed agent must give before contract. Article 35, paragraph 1, item 14 of the Real Estate Brokerage Act defers to ministerial ordinance, splitting by counterparty rather than by contract type: sub-item (a) covers matters protecting an individual buying or renting otherwise than in the course of business and runs to a joint MLIT and Cabinet Office ordinance, sub-item (b) covers everything else and runs to an MLIT ordinance. Both land on the same provision, and Article 16-4-3, item 2 of the Enforcement Regulation names a 土砂災害警戒区域 designated under Article 7, paragraph 1. Item 2 falls inside the range that applies to all four contract types the article lists, sales and exchanges and leases of land and of buildings alike. Because a red zone is always inside a yellow zone, that item catches it too.

The red zone's restrictions arrive through a different door: Article 35, paragraph 1, item 2 covers restrictions under laws listed by Cabinet Order, and Article 3, paragraph 1 of the Enforcement Order names Article 10, paragraph 1 and Article 17, paragraph 1 of the 土砂災害防止法, for contracts other than leases. The same list also names the 急傾斜地法 restrictions.

Two limits on relying on this. The duty binds a licensed agent (宅地建物取引業者), so a genuinely direct private sale with no agent, common on municipal akiya bank listings, carries no such duty at all. And the explanation is given before contract, which is later than you want to know. Treat the check as yours.

Here is how to confirm the position on a specific parcel.

1. Get the lot number (地番) first. Zone boundaries are geographic and are published against maps, so you need to locate the parcel precisely, and rural slope land often has no postal address. Our free lot number lookup and the guide to finding a lot number cover this.
2. Screen it on the national portal, then stop trusting the screen. The Hazard Map Portal Site at disaportal.gsi.go.jp overlays sediment disaster zones on a national base map, and MLIT's own public guidance tells residents to check there. It is the right first look and the wrong last word: a portal layer is a periodic snapshot drawn at map scale, and your question is whether a particular parcel boundary falls inside a particular zone boundary.
3. Go to the prefecture that made the designation. The designating authority is the prefectural governor, and MLIT maintains a list of links to every prefecture's sediment disaster pages, most of which run a zone viewer. MLIT also publishes the designations as GIS data through National Land Numerical Information. Ask the prefecture's sediment control division (砂防主管課, names vary) whether the parcel is in a yellow zone, whether it is in a red zone, and which of the three causes the designation was made for.
4. Ask to see the documents held at the municipal office. Article 9, paragraph 5 requires the governor to send the municipality the documents recording a red-zone designation, and Article 9, paragraph 7 requires the mayor to make them available for public inspection at the municipal office. That inspection right is written for red zones specifically. Article 7, paragraph 5 requires the equivalent documents to be sent for a yellow zone, but Article 7 sets no public inspection duty, so for a yellow zone ask the prefecture or the municipality directly rather than assuming a counter inspection is available.
5. If it is red, ask how much of the site is inside, then get the numbers. On a parcel the boundary crosses, the share of the site inside the zone is what decides whether a building confirmation is required at all, under Article 91 as applied by Article 25, while the wall standard turns on whether any part of the building is inside. Ask the prefecture for the zone boundary against your parcel, not just a yes or no. Then ask for the type of phenomenon, the maximum assumed force and the assumed sediment or debris-flow height fixed for that part of the zone under Article 9, paragraph 2 and Article 4 of the Enforcement Order. Those three values are the inputs to the Article 80-3 structural requirement, your designer cannot price the walls without them, and they are the reason two red-zone parcels can carry very different construction costs. Ask at the same time whether a blocking wall or gate under the Article 80-3 proviso is a route the prefecture accepts here.
6. Describe your actual plan, because the permit turns on it. The useful question is not "is this a red zone" but "given what I intend to build, is this a 特定開発行為". A house you will live in as your main home is not. A holiday home is, because prefectural guidance does not treat a second home as a main base of life. So is the same house built to rent or to sell, if the work changes the division, form or quality of the land. A guest house, a care facility, a clinic or a kindergarten changes the answer again. Put the intended use in writing when you ask, and say plainly whether the house will be your main home, because that single fact decides whether you need the permission at all.
7. Ask about 災害危険区域 ordinances separately, and ask both bodies. A 災害危険区域 under Article 39 of the Building Standards Act is made by ordinance of a 地方公共団体, which may be the prefecture or the municipality depending on where you are, and it can prohibit housing outright. Osaka Prefecture designates its own by prefectural ordinance and ties it to steep-slope collapse danger; elsewhere the city does it. Neither a sediment-disaster zone answer nor the national portal's sediment layers will cover it, so put the question to the prefecture's building division and the municipality's, and do not assume one of them speaks for the other.
8. Ask for the important matters explanation section by name, and do not rely on it. Where a licensed agent is involved, ask specifically for the Article 16-4-3, item 2 disclosure and for the item 2 restrictions on development. Where the sale is direct and unbrokered, nobody owes you either.
9. Put the answer in the contract. If your purchase depends on being able to build what you intend, make it conditional on written confirmation from the prefecture and the municipality, with a deadline. A seller's reassurance that "the zone does not matter" is worth nothing against a refused building confirmation.

The most common mistake is treating the yellow and red zones as a severity scale for the same restriction. They are different instruments: the yellow zone regulates the municipality's warning and evacuation arrangements, and the red zone regulates development, building confirmation and structure. The second mistake is the mirror image, assuming a red zone means you cannot build. You usually can build a home you will live in yourself, and what you face instead is a building confirmation you might otherwise not have needed, an engineered wall specification wherever part of a building with a habitable room sits inside the zone, and a slope that the prefecture has formally assessed as able to destroy a house. A fourth mistake belongs with it: reading the confirmation requirement and the wall standard as one rule. The confirmation follows the majority of the site and the wall standard follows the building, so a boundary parcel can owe the engineering without owing the confirmation. The third is treating an undesignated slope as a safe slope. Designation requires a survey, the criteria are geometric, and a slope just under 30 degrees or a stream catchment just over 5 square kilometres falls outside the criteria without becoming safe.

What the property registration record can and cannot tell you here:

• What it shows reliably: the lot number, the registered land category, the registered area, the current owner, and any mortgages, seizures or other registered rights, all as of the date of the record. On slope land, confirming the ownership position matters more than usual, because inherited hillside parcels are frequently still registered to a deceased ancestor.
• What it does not show: anything about either zone. Neither a 土砂災害警戒区域 nor a 土砂災害特別警戒区域 designation is recorded in the property register. Both take effect by public notice from the prefectural governor, and both live in the prefecture's designation records and the documents sent to the municipality. A clean registration record tells you nothing at all about landslide designation, and the registered land category does not either: 宅地 is not evidence that a parcel escaped designation.
• What the zone records do not show either: whether a permission under Article 10 has ever been sought, granted or refused on the parcel, whether a relocation recommendation under Article 26 has been made to the current owner, or what a prefectural or municipal ordinance adds under Article 39 of the Building Standards Act. Ask for each by name.
• How to order the record: use the free lot number lookup to identify the parcel, then order the land registration record for ¥1,500. If there is a building on the land, order the building record too, since land and buildings are registered separately in Japan. Both are delivered by email and saved to your account. Our guide to ordering registration records in English explains the process.

The registration record is the right first step even though it is silent on the hazard question, because the lot number, the registered area and the ownership position are what you need before you can ask the prefecture anything useful. The zone enquiry is keyed to a location, and the register is what fixes which location you are asking about. Run both, and record the result in your due diligence checklist alongside road frontage, boundaries and zoning. Our guide to checking zoning and hazard maps covers the wider map review this sits inside.

Where a designation exists and your plans depend on building, confirm the position in writing with the prefecture's sediment control division and the municipality's building department, and take advice from a licensed architect (建築士) on the Article 80-3 structural requirement before you commit. For anything that turns on the parcel's exact boundary against the zone boundary, a land and house investigator (土地家屋調査士) is the right professional.

FAQ

Does a 土砂災害警戒区域 designation stop me building a house? No. A yellow-zone designation carries no permit requirement, no building restriction and no structural standard for an ordinary owner. Its legal effect is to require the municipality to put warning and evacuation arrangements in its regional disaster management plan under Article 8 and to make them known to residents, and to require a licensed agent to disclose the designation before contract. What you should take from it is that the prefecture has assessed this ground as capable of harming someone, and that a municipal hazard map very probably covers it, though about 4 percent of surveyed zones were not yet shown on one at the end of March 2026, so check the prefecture's designation records rather than treating an empty map layer as an answer.

Can I build my own house in a 土砂災害特別警戒区域? In principle yes, if it will be your main home. The Article 10 development permit then does not apply to you, because the restricted uses under Article 10, paragraph 2 are housing other than housing for the developer's own residence, plus the welfare, special-needs school, kindergarten and medical facilities specified in Article 6 of the Enforcement Order. Be careful with that carve-out if you are buying from abroad: prefectural guidance reads 自己の居住の用 as the developer's own main base of life, and Shimane Prefecture's manual puts a holiday home outside it expressly, so a second home in a red zone is a restricted use and needs the permission where the work changes the division, form or quality of the land. Second, a building confirmation you would otherwise escape can become compulsory, and the structural standard applies to the walls. Article 25 deems a building with a habitable room in a red zone to sit in a governor-designated area under Article 6, paragraph 1, item 3 of the Building Standards Act, and it also switches on Article 91, so the confirmation requirement follows the area containing the majority of the site: on a boundary parcel where most of the site is outside the zone, no confirmation arises from this route. The structural rule is separate and stricter. Where any part of the building is inside the zone, the external walls and main load-bearing parts must meet the method set under Article 80-3 of that Act's Enforcement Order, whether or not a confirmation is required, unless a qualifying blocking wall or gate is in place. Budget for the engineering, and get the designation's assumed force and sediment height from the prefecture before you ask a designer for a price.

I am buying a house that already stands in a red zone. Do I have to engineer the walls? Not as a condition of owning it. Article 3, paragraph 2 of the Building Standards Act puts a building that already existed when the provision became applicable outside that provision, so a house built before the red zone was designated is 既存不適格 (existing nonconforming) rather than unlawful, and the Article 80-3 standard is not a retrofit order. MLIT treats these buildings as a recognised category and runs a subsidy programme for them. What can end the protection is triggering work: Article 3, paragraph 3, item 3 withdraws it for an extension, rebuild, relocation, major repair or major alteration begun after the provision applies. Even then it may survive. Article 86-7, paragraph 1 continues the non-application of Article 20, which is what the wall standard is made under, for an extension, rebuild, major repair or major alteration within the range the Enforcement Order sets for that kind of work: Article 137-2 for an extension or rebuild, with the structural standards there, and Article 137-12, paragraph 1 for a major repair or major alteration, which covers all such work that does not increase the building's structural danger. A relocation has its own route in Article 86-7, paragraph 4 with Article 137-16. So ask the building authority which range your work falls in rather than assuming either that nothing is owed or that the walls must be rebuilt on purchase.

Is the designation on the property registration record? No. Neither zone appears on the register. The designation is made by the prefectural governor and takes effect by public notice, and the record of it sits with the prefecture and in the documents sent to the municipality. The register is still the right first order, because it gives you the lot number, area and ownership you need to ask the prefecture the question.

What is the difference between this and a 急傾斜地崩壊危険区域? Different statute and a different target. A 急傾斜地崩壊危険区域 is designated under Article 3 of the 急傾斜地法, and Article 7 requires the governor's permission for acts that could promote or trigger a collapse: discharging or retaining water, installing or altering facilities or structures other than slope-protection works, cutting, excavating or filling, felling trees and bamboo, and extracting or stockpiling earth and stone. Its Enforcement Order then exempts more than small works: a set of ordinary water uses, removal cutting and the felling of fallen or dead trees and bamboo, size-limited works near the slope, and acts already authorised under other statutes. It regulates what you do to the slope. The 土砂災害防止法 zones regulate warning arrangements and, in the red zone, development and building structure. A parcel can be in both, and a prefecture may answer about one and not the other unless you ask about each.

Can the designation be lifted? A red zone can, and the statute is unusually firm about it: Article 9, paragraph 8 provides that the governor shall release all or part of a 特別警戒区域 once the grounds for designation have ceased to exist, which typically means after sediment control works are built. For a yellow zone, Article 7, paragraph 6 applies the designation procedure to release but sets no equivalent duty. Do not plan a purchase around a release unless the prefecture confirms that works are actually funded and programmed.

Can the government force me to move out of a red zone? No. Article 26 gives the governor a power to recommend (勧告) relocation or other risk-reduction measures to the owner, manager or occupier of a building with habitable rooms, where the risk of serious harm is judged high. A recommendation is not an order, and paragraph 2 requires the governor to endeavour to provide assistance, such as brokering the acquisition of land, where that is needed.

Does the designation entitle me to compensation if it lowers the value? No. Shimane Prefecture's manual on the permit system addresses this directly: the designation exists to make an existing natural risk in the land visible and to impose the minimum necessary restrictions on development and building, and there is in principle no compensation if the land's value falls as a result. Treat the designation as information about the ground you are buying, and reflect it in the price you offer rather than expecting it to be made good later.

The listing is not in a designated zone. Is the land safe? Not necessarily, and this is the trap on the optimistic side. The criteria are geometric. Article 2 of the Enforcement Order defines the steep-slope case as a slope of 30 degrees or more and at least 5 metres high, with the zone running 10 metres horizontally beyond the top edge and, below the bottom edge, twice the slope height to a maximum of 50 metres; the debris-flow case as a stream with an upstream catchment of 5 square kilometres or less, from the fan apex downstream, where the measured land gradient is 2 degrees or more; and the landslip case as the slide area plus an adjacent band extending up to 250 metres in the slide direction. Ground that falls just outside a threshold is outside the designation, not outside the hazard. The answer is also only current: the survey behind the designations runs roughly every five years under Article 4, paragraph 1, so land not designated today can be designated later, and a yellow zone can become a red one at a later survey. Read the municipal hazard map and the topography as well as the designation.

Who do I actually call? The prefecture's sediment control division for the designation, its cause, the zone boundary against your parcel and the red-zone force and height values; the municipality's building department for building confirmation, and both the prefectural and the municipal building divisions for any 災害危険区域 ordinance, since either body may be the one that designated it; and the municipality's disaster management section for the hazard map and the evacuation arrangements. MLIT's per-prefecture link list is the fastest way to find the first of those.

Related guides:

• How To Check Zoning And Hazard Maps In Japan
• How To Check If A Japanese Property Is Rebuildable
• How To Check If Japanese Land Is Protected Forest
• Japan Property Due Diligence Checklist

• e-Gov: Act on Promotion of Sediment Disaster Countermeasures for Sediment Disaster Prone Areas (土砂災害防止法), Act No. 57 of 2000. Digital Agency e-Gov law database, official. Article 2 (definition of 土砂災害 and the 30-degree steep slope), Article 4 (the 基礎調査 roughly every five years, and publication of its results), Article 7 (yellow zone designation, per-cause designation, notice and documents), Article 8 (municipal plan contents and the duty to inform residents), Article 8-2 (evacuation plans for facilities used by people needing special care), Article 9 (red zone designation, the values it must fix, effect on notice, public inspection at the municipal office, and mandatory release), Article 10 (the 特定開発行為 permission and the restricted uses), Article 19 (building bar until completion is notified), Articles 24 and 25 (structural strength standard and the application of the Building Standards Act), Article 26 (relocation recommendation and assistance), Article 38 (one year or ¥500,000), Article 42 (¥200,000 civil fine).
• e-Gov: Order for Enforcement of the 土砂災害防止法, Cabinet Order No. 84 of 2001. Digital Agency e-Gov law database, official. Article 2 (yellow zone criteria: 30 degrees and 5 metres, the 10-metre upper band, twice the height capped at 50 metres below, the 5 square kilometre catchment and 2-degree gradient for debris flow, the 250-metre landslip band), Article 3 (red zone criteria), Article 4 (the force and height values recorded in a designation), Article 5 (exempt development), Article 6 (the specified welfare, school and medical facilities).
• e-Gov: Building Standards Act, Act No. 201 of 1950. Digital Agency e-Gov law database, official. Article 3, paragraphs 2 and 3 (existing nonconforming buildings, and the loss of that protection on an extension, rebuild, relocation, major repair or major alteration), Article 6, paragraph 1 (the three categories requiring building confirmation) and paragraph 2 (the 10 square metre exemption), Article 39 (災害危険区域 ordinances made by a 地方公共団体), Article 86-7, paragraph 1 (continued non-application of Article 20 for qualifying work on an existing nonconforming building, notwithstanding Article 3, paragraph 3, items 3 and 4) and paragraph 4 (qualifying relocations, reaching the Building Standards Act provisions generally), Article 91 (the majority-of-site rule where a site straddles an area boundary).
• e-Gov: Order for Enforcement of the Building Standards Act, Cabinet Order No. 338 of 1950. Digital Agency e-Gov law database, official. Article 80-3 (the structural method for buildings with habitable rooms in a red zone, and the blocking wall proviso), Article 137-2 (the qualifying ranges and standards for extensions and rebuilds of buildings outside Article 20 of the Act), Article 137-12, paragraph 1 (major repairs and major alterations that do not increase structural danger), Article 137-16 (qualifying relocations).
• e-Gov: City Planning Act, Act No. 100 of 1968. Digital Agency e-Gov law database, official. Article 4, paragraph 12 (definition of 開発行為), Article 33, paragraph 1, item 8 (development areas and 災害危険区域等, the own-residence carve-out and the proviso).
• e-Gov: Real Estate Brokerage Act, Act No. 176 of 1952. Digital Agency e-Gov law database, official. Article 35, paragraph 1, item 2 (restrictions under laws listed by Cabinet Order) and item 14 with its (a) and (b) split by counterparty.
• e-Gov: Regulation for Enforcement of the Real Estate Brokerage Act, Ministry of Construction Ordinance No. 12 of 1957. Digital Agency e-Gov law database, official. Article 16-4-3, item 2 (disclosure of a yellow zone) and the contract types each item applies to.
• e-Gov: Order for Enforcement of the Real Estate Brokerage Act, Cabinet Order No. 383 of 1964. Digital Agency e-Gov law database, official. Article 3, paragraph 1 (restrictions under the 土砂災害防止法 and the 急傾斜地法 as matters for the important matters explanation).
• e-Gov: Act on Prevention of Disasters Caused by Collapse of Steep Slopes (急傾斜地法), Act No. 57 of 1969. Digital Agency e-Gov law database, official. Article 3 (designation), Article 7 (restricted acts, the permission, and the 14-day notification).
• e-Gov: Order for Enforcement of the 急傾斜地法, Cabinet Order No. 206 of 1969. Digital Agency e-Gov law database, official. Article 2 (the acts exempted from permission, including the small earthworks thresholds).
• Shimane Prefecture: manual on the 特定開発行為 permit system under the 土砂災害防止法 (PDF). Shimane Prefecture, official. That 自己の居住の用に供する住宅 means a house used as the owner's own base of life (生活の本拠), that dormitories, company housing, co-operative transfer housing and a holiday home (別荘) fall outside it, and the stated reason for the carve-out. Also, from its Q&A: that an artificial slope is covered where a natural collapse could occur, that no on-site marker is legally required, that a red zone can cover land with no houses on it, that a later survey can turn a yellow zone red, that there is in principle no compensation for a fall in value, and the cause-side versus affected-area distinction against the older designations.
• Shizuoka Prefecture: FAQ on sediment disaster hazard zones. Shizuoka Prefecture, official. That a 特定開発行為 is development for housing other than the developer's own, with subdivided housing, apartment blocks and company housing as the examples.
• Okinawa Prefecture: buildings with habitable rooms in a 土砂災害特別警戒区域. Okinawa Prefecture, official. That a confirmation is required where the building is wholly or partly in the red zone and the majority of the site is in it, that the structural regulation still applies where the building is partly in the zone even when no confirmation is required, and the structural method notification 平成13年国土交通省告示第383号. (The page cites the pre-2025 numbering of Building Standards Act art. 6, paragraph 1, item 4 for small buildings outside city planning areas; the equivalent today is item 3.)
• Osaka Prefecture: building permission inside a 災害危険区域. Osaka Prefecture, official. An example of a prefecture, rather than a municipality, designating under Building Standards Act art. 39, tied to steep-slope collapse danger, with some cities in the prefecture designating under their own ordinance.
• MLIT: relaxation of restrictions on existing buildings. Ministry of Land, Infrastructure, Transport and Tourism. The Article 86-7 relaxations for qualifying extensions and other work on existing nonconforming buildings.
• MLIT: support for existing nonconforming buildings in sediment disaster special hazard zones. Ministry of Land, Infrastructure, Transport and Tourism. That existing nonconforming red-zone buildings are a recognised category with a subsidy programme behind them.
• MLIT: national designation status of sediment disaster hazard zones, as of 30 June 2026 (PDF) and the accompanying definitions sheet (PDF). Ministry of Land, Infrastructure, Transport and Tourism. The 721,014 and 621,287 totals, the per-cause breakdown, the single landslip red zone, and MLIT's own yellow and red labelling.
• MLIT: 土砂災害危険箇所. Ministry of Land, Infrastructure, Transport and Tourism. The retirement of the legacy hazard-location dataset and the statement that nationwide zone designation is broadly complete.
• MLIT: publication status of sediment disaster hazard maps, as of end of March 2026 (PDF). Ministry of Land, Infrastructure, Transport and Tourism. The 1,602 municipalities that have designated or plan to designate a zone, and that approximately 100 percent of them publish a hazard map.
• MLIT: coverage of hazard maps by zone, as of end of March 2026 (PDF). Ministry of Land, Infrastructure, Transport and Tourism. The 96 percent of surveyed zones shown on a hazard map, counted once per municipality a zone spans.
• MLIT: links to prefectural sediment disaster information. Ministry of Land, Infrastructure, Transport and Tourism.
• MLIT: explanation of 急傾斜地崩壊危険区域. Ministry of Land, Infrastructure, Transport and Tourism. The designation, the restricted acts, and that the permission rules are implemented through prefectural ordinances.
• Hazard Map Portal Site. Geospatial Information Authority of Japan and MLIT.
• MLIT: National Land Numerical Information. Ministry of Land, Infrastructure, Transport and Tourism. The designations as GIS data.