Japan's 1981 Seismic Code (Shin-Taishin): Full Guide

1981: the kenchiku kijun-hō reform that changed everything

On 1 June 1981, Japan thoroughly revised its Building Standards Act (kenchiku kijun-hō, Kenchiku kijun hō). The reform introduced the new seismic standard — shin-taishinkijun (shin-taishin kijun), as opposed to the old one — kyū-taishinkijun (kyū-taishin) — applicable before that date.

The difference is not cosmetic, it is structural:

• kyū-taishin (before 1 June 1981): goal = withstand a moderate quake, around shindo5, without major damage. Behaviour in a large earthquake is not guaranteed.
• shin-taishin (from 1 June 1981): goal = not collapse in a major earthquake of around shindo6kyō to 7, to protect human lives, while remaining repairable after a moderate quake.

This 1981 threshold is the seasoned investor's first reflex: it drives safety, insurance, financing and resale. We factor it into every property analysis, alongside natural hazards and the hazard map.

Checking the date: kenchiku kakunin, not just chikunensū

A classic mistake: looking only at the construction year (chikunensū, chikunensū) shown in the listing. What matters legally is the date of the building permit — kenchiku kakunin (kenchiku kakunin), not the completion date.

A building completed in 1982 or 1983 may well have received its kenchiku kakunin before 1 June 1981: it is then kyū-taishin, despite a reassuring completion date. The gap between permit and delivery can reach one to two years on large buildings.

How to check in practice

• Ask for the building permit certificate (kenchiku kakunin-zumishō) or the final inspection certificate (kensa-zumishō).
• Review the property register (tōki) and the property documents.
• Have the kenchiku kakunin date stated in the jūyō jikō setsumei (mandatory explanatory document handed over before the sale).

In practice, a safety rule applies: to be confident about shin-taishin, target a property whose permit is after 1 June 1981 — for condominiums (mansion (copropriété)), many buyers give themselves a margin by targeting buildings delivered from 1983-1984 onward.

Diagnose and reinforce: taishin shindan and taishin hokyō

A kyū-taishin property is not necessarily one to avoid: many have been reinforced, and a well-executed upgrade can protect the occupant while creating value.

The seismic diagnosis (taishin shindan)

The taishin shindan (taishin shindan) is an assessment carried out by a licensed architect (kenchikushi) who evaluates the building's real resistance and assigns an index (the Is value for concrete). It shows whether the property meets the shin-taishin level, and what would need to be done.

The reinforcement (taishin hokyō)

The taishin hokyō (taishin hokyō) covers upgrade works: bracing, wall and foundation reinforcement, anchoring. On an older wooden house, this often goes hand in hand with a heavy renovation — we break down the costs in our article on the cost of renovating a machiya / kominka.

Municipal subsidies often exist for taishin shindan and taishin hokyō of kyū-taishin properties: check with the property's city hall (shiyakusho), as they can significantly lighten the bill.

kyū-taishin vs shin-taishin vs 2000: the table to remember

The code saw a second major revision in 2000 (2000年kijun), specifically for wooden houses (mokuzō), after the Kobe earthquake (1995): stronger anchoring, clearer balance of load-bearing walls, ground study. For a detached wooden house, this 2000 threshold is almost as important as 1981.

Standard	Period (permit kenchiku kakunin)	Target quake	Key point
kyū-taishinkijun	Before 1 June 1981	≈ shindo5 (moderate)	Collapse possible in a large quake; diagnosis advised
shin-taishinkijun	From 1 June 1981	≈ shindo6kyō–7 (major)	Non-collapse targeted; reference standard
2000年kijun (wood)	From June 2000	≈ shindo6kyō–7, reinforced wood	Anchoring + wall balance; ideal for a wooden house

Memory aid: 1981 for all buildings, 2000 on top for wood. Always cross this criterion with the real risk exposure on the hazard map.

Real impact: jishin hoken insurance, financing and discount

The 1981 code is not only about safety: it has direct financial effects.

Earthquake insurance (jishin hoken)

Earthquake insurance (jishin hoken) applies premium discounts based on seismic performance: a shin-taishin or reinforced property, or one certified by a diagnosis, enjoys better rates than an unreinforced kyū-taishin.

Financing

For a buyer who can borrow — recall that Japanese mortgages are reserved for people both resident AND salaried in Japan, non-residents buy in cash — a kyū-taishin property is often harder to finance (shorter term, discount applied by the bank).

Discount… and opportunity

A kyū-taishin property usually sells cheaper: that is a risk, but also an opportunity for those who budget the reinforcement. It is common on akiya (vacant houses): the low price can absorb a taishin hokyō, provided the location is good (station ≤ 20-30 min + shops).

Common mistakes

• Trusting the chikunensū instead of the kenchiku kakunin date.
• Buying a kyū-taishin without pricing the taishin hokyō.
• Forgetting, for a wooden house, the 2000 threshold.
• Neglecting the link with the hazard map and soil type.

In short: 1981, the first filter of a safe purchase

The 1981 seismic code (shin-taishinkijun) is the first filter of any property purchase in Japan: it separates buildings designed not to collapse in a major quake (shindo6kyō–7) from earlier ones calibrated for a moderate quake (shindo5). Check the date via the kenchiku kakunin, not the chikunensū; for a wooden house, add the 2000 threshold.

A kyū-taishin is not disqualifying: well diagnosed (taishin shindan) and reinforced (taishin hokyō), at a discounted price and in a good location, it can become a fine deal. The full buying guide places this criterion within due diligence; browse real properties in our hand-picked listings. To have all this diagnosed, priced and secured, discover our personalised buying support.

Frequently asked questions

What is Japan's 1981 seismic code (shin-taishin)?

It is the revision of the kenchiku kijun-hō that came into force on 1 June 1981, introducing the new seismic standard (shin-taishinkijun). A building designed after that date must withstand a major earthquake (shindo6kyō to 7) without collapsing, whereas the old standard (kyū-taishin) only targeted a moderate quake (shindo5).

How do I know if a property is kyū-taishin or shin-taishin?

Do not rely on the construction year (chikunensū): what matters is the building permit date (kenchiku kakunin). A building delivered in 1982-1983 may have a permit before 1 June 1981, hence kyū-taishin. Ask for the kenchiku kakunin-zumishō certificate and have the date stated in the jūyō jikō setsumei.

Should I avoid buying a kyū-taishin property?

Not necessarily. A kyū-taishin can be diagnosed (taishin shindan) and reinforced (taishin hokyō); it sells cheaper, which leaves a budget for the upgrade. It is even an opportunity if the location is good. Always price the reinforcement before buying, and check for municipal subsidies.

What is the difference between the 1981 and the 2000 code?

1981 (shin-taishin) applies to all buildings. In 2000 (2000年kijun), a second revision specifically strengthened wooden houses (mokuzō) after the Kobe earthquake: anchoring, load-bearing wall balance, ground study. For a detached wooden house, targeting a permit after 2000 is a real plus.

Does the 1981 code affect earthquake insurance and financing?

Yes. A shin-taishin or reinforced property enjoys lower earthquake insurance (jishin hoken) premiums. On financing, a kyū-taishin is often harder to fund (shorter term, discount) — bearing in mind Japanese mortgages are reserved for salaried residents, with non-residents buying in cash.