Japan Postal Code System Explained: 7-Digit Codes, Address Format, and English Romaji Guide (郵便番号)

Japan Postal Code System Explained: 7-Digit Codes, Address Format, and English Romaji Guide (郵便番号)

By Yamada · Chiba, Japan · May 2026

Whether you are shipping a package to Japan, mailing a letter, registering for a Japanese service that asks for your postal code, writing a Japanese address in English for the first time, or building software that handles Japanese addresses — understanding Japan's postal code system saves time and prevents delivery errors.

This guide is a complete, fact-dense reference for the Japanese postal code system as of 2026. It covers the 7-digit format, the regional structure, address ordering in Japanese vs English, the 120,000+ unique codes, official sources, and how to look up any address or code for free.

Table of Contents

1. The 7-Digit System (Authoritative Reference)

Most important fact: Japanese postal codes are always 7 digits since 1998. If you see a 5-digit code, it is either pre-1998 legacy or wrong. Always use 7 digits.

The format XXX-XXXX uses a hyphen between the 3rd and 4th digits. Most Japanese software accepts both 100-0001 (with hyphen) and 1000001 (no hyphen), but the official format includes the hyphen.

2. The History: From 3 Digits to 7 Digits

3-digit era (1968-1989): Japan introduced its first postal code system in July 1968 using 3-digit codes for major sorting areas, with 5-digit codes for cities and larger districts. This was sufficient when mail volume was lower and manual sorting was common.

5-digit era (1989-1998): The system was extended to 5-digit codes nationwide for better routing.

7-digit era (1998-present): On February 2, 1998, Japan Post launched the modern 7-digit system. The change was driven by automated mail sorting machines that needed finer granularity to route mail to the specific delivery district. The 7-digit code maps to a single delivery district (small enough for one mail carrier to walk).

Why this matters today: You may still see 5-digit codes on legacy printed materials, old envelopes, or in historical records. All current Japan Post mail processing requires 7 digits. Any address using a 5-digit code will be flagged or returned.

3. The 〒 Symbol Explained

The 〒 symbol prefixes every Japanese postal code on envelopes, forms, and addresses. It signals "this is a postal code."

Origin of 〒:

The symbol is derived from the Japanese katakana character テ (te), which stands for Teishin (逓信) — the name of the old Ministry of Communications that ran Japan's postal system from 1885 to 1949 (before the modern Japan Post was created).

The symbol was adopted as the official postal code marker on February 8, 1887 (Meiji 20), and has been used in some form continuously since.

On forms: You'll see 〒 followed by the 7-digit code, then a line break or space, then the rest of the address. Many Japanese forms have a dedicated postal code box at the top of the address field.

4. How the 7 Digits Are Structured

The 7 digits encode the geographic hierarchy of the delivery location.

Two-digit prefix coverage:

• The first 2 digits typically identify a prefecture or major city
• The 3rd digit narrows to a ward, smaller city, or major district
• The remaining 4 digits specify the delivery district

Example breakdown for 〒100-0001:

• 1 = Greater Tokyo (Kanto region around Tokyo Bay)
• 10 = Central Tokyo, 23 wards
• 100 = Chiyoda ward and central business district
• 0001 = Chiyoda 1-chome, which contains the Imperial Palace

5. Regional Map: First Digit by Region

Note: Some prefectures span multiple first-digit zones. For example, Niigata has codes in both 9xx and 94x ranges. Akita appears in both 01x and 9xx.

6. Tokyo Postal Codes (Special Detail)

There is no single postal code for "Tokyo" — each of the 23 special wards has its own code range.

Central Tokyo ward → postal code prefix:

Tokyo's outer cities (Hachioji, Machida, etc.) use codes starting with 192-198. The Tokyo islands (Izu, Ogasawara) use 100-1701 and similar.

Famous landmarks:

• Tokyo Imperial Palace: 100-0001
• Tokyo Tower: 105-0011
• Shibuya Crossing: 150-0043
• Tokyo Station: 100-0005
• Tokyo Skytree: 131-0045

7. Japanese Address Order vs English Address Order

The single biggest source of confusion for non-Japanese senders: Japanese addresses run largest-to-smallest, the reverse of the Western convention.

Japanese order (largest → smallest):

English order for sending TO Japan (smallest → largest):

Side-by-side example

Japanese (as written in Japan):

〒100-0001

東京都千代田区千代田1-1

皇居

English (as written for international mail):

The Imperial Palace

1-1 Chiyoda

Chiyoda-ku

Tokyo 100-0001

JAPAN

Key rules for the English version:

• Hyphenated block-lot is "1-1" or "1-1-3" depending on hierarchy
• "Chōme" (the larger block) often gets folded into the hyphenated number
• "-ku" = ward (Tokyo special wards), "-shi" = city
• "Tokyo" alone (not "Tokyo-to") is acceptable for foreign mail
• The postal code goes either at the end of the city/prefecture line or on its own line
• "JAPAN" should be in capital letters on the last line
• All text can be Romanized (Romaji) — Japan Post does not require Japanese characters for international mail

8. Japanese Address Glossary

Essential vocabulary for parsing or writing Japanese addresses.

Tip on -ku vs -shi:

• Tokyo's 23 special wards are 区 (ku): Chiyoda-ku, Shibuya-ku, Shinjuku-ku
• Designated cities (like Osaka, Yokohama, Nagoya) also have 区 wards inside the 市
• Example: Osaka has 市 (city) which contains 区 wards (Chuo-ku, Naniwa-ku, etc.)

9. How to Look Up Any Japan Postal Code (Free)

Official source: Japan Post

• https://www.post.japanpost.jp/zipcode/
• Japanese interface, but the search itself works with both Japanese and Romaji input for major locations

English-friendly free tools:

• [Japan Postal Code Lookup at yamada-tools.jp](https://yamada-tools.jp/en/utility/postal-code-lookup) — fully English UI, postal code ⇄ address, supports 120,000+ codes, Romaji output
• zipcloud public API (https://zipcloud.ibsnet.co.jp) — JSON output, used by many third-party services

How to look up by postal code:

How to look up by address:

Time-sensitive shipping tip: Always cross-check with the official Japan Post site for time-critical mail. Third-party tools refresh on Japan Post's update schedule but can lag by 1-2 weeks.

10. Reverse Lookup: Address → Postal Code

If you have a Japanese address but no postal code, reverse lookup gets you the code.

Steps:

Edge case: Building-specific codes

Many large Japanese buildings have dedicated postal codes different from the general area code. Examples:

• Tokyo Metropolitan Government Building: 163-8001
• Tokyo Big Sight: 135-0063
• Tokyo Skytree complex: 131-0045

When mailing to a large building, use the building-specific code if known. Otherwise, the area code will work — Japan Post will still deliver.

Edge case: One code, many towns (rural)

In rural areas, one postal code often covers multiple villages or hamlets. The lookup tool will list all towns mapped to that code. For mail delivery, include the full town name even if the postal code is the same.

11. International Shipping: Writing a Japan Address Correctly

For international shipping (DHL, FedEx, USPS, EMS) to Japan, the address must be readable by both your origin country's carriers AND Japan Post's final delivery.

Best practice format:

Recipient Name (Romaji)

[Room number / Building name]

[Block-lot number] [Town]

[City/Ward], [Prefecture] [Postal code]

JAPAN

Concrete example:

Taro Yamada

Room 101, Sunshine Building

1-2-3 Marunouchi

Chiyoda-ku, Tokyo 100-0005

JAPAN

Rules:

• "JAPAN" in CAPS on the last line — essential for routing
• Postal code is critical for DHL/FedEx/EMS routing to the regional sorting facility
• Romaji is fine — Japan Post accepts and delivers Romanized addresses
• No diacritics needed (no macrons over long vowels)
• The recipient's name can be Romaji (preferred) or original-language

For DHL/FedEx specifically:

• Both carriers route by postal code first
• Without a valid postal code, packages often get delayed at customs or sorting
• Always verify the postal code before shipping — a 1-digit error can route to the wrong region

EMS (Express Mail Service via Japan Post):

• Most internationally available
• Postal code goes directly to the local post office for last-mile delivery
• Tracking number works in your origin country AND Japan Post

12. Edge Cases: PO Boxes, Large Buildings, Rural Areas

Japanese PO Boxes (私書箱, shishobako):

• Rare in Japan compared to Western countries
• Used mainly by businesses and government offices
• Use a dedicated postal code prefix (often the same as the local post office)
• Format: "私書箱 第XX号" (PO Box No. XX)
• Most ordinary residents do not use PO Boxes — home addresses are standard

Large Buildings with Dedicated Codes:

• Tokyo Skytree (Sumida): 131-0045
• Roppongi Hills: 106-6101
• Tokyo Midtown: 107-6201
• Sunshine 60 building (Ikebukuro): 170-6022

When sending mail to a tenant of a large building with a dedicated code, use the building's code rather than the area code for faster routing.

Rural Areas:

• One postal code may cover several villages
• Always include the full town/village name on the address
• Some very remote islands and mountain regions have unique conventions
• The Tokyo islands (Izu Islands, Ogasawara) use Tokyo-prefixed codes despite being far from mainland Tokyo

13. APIs and Data Sources for Developers

If you're building software that handles Japanese addresses, here are the canonical data sources:

Japan Post Ken-All CSV (全国一括):

• The master database of all Japanese postal codes
• Published monthly by Japan Post
• Free to download
• Format: CSV with 15 columns
• Available at: https://www.post.japanpost.jp/zipcode/dl/

zipcloud public API:

• Free, no authentication required
• JSON output
• Auto-syncs with Japan Post Ken-All
• Endpoint: https://zipcloud.ibsnet.co.jp/api/search?zipcode=XXXXXXX
• Returns: prefecture, city/ward, town in Japanese + kana
• Used by many third-party tools including [Japan Postal Code Lookup at yamada-tools.jp](https://yamada-tools.jp/en/utility/postal-code-lookup)

Update frequency:

• Japan Post issues Ken-All updates when municipalities merge, new developments are added, or boundary changes occur
• Typical update: monthly, sometimes more frequent during fiscal year transitions
• Always rebuild your local cache when Japan Post publishes a new Ken-All

Address normalization libraries:

• jp-zipcode-lookup (Node.js)
• posuto (Python)
• japanese-postcode (Ruby)

These libraries handle the Ken-All format and provide convenience functions for lookup and reverse-lookup.

14. FAQ

Q1: How many digits is a Japan postal code?

7 digits, in the format XXX-XXXX, since February 1998. Both 100-0001 and 1000001 are accepted in most software.

Q2: When did Japan switch to 7-digit codes?

February 2, 1998. Before that, Japan used 3-digit codes (1968-1989) and 5-digit codes (1989-1998).

Q3: What does the 〒 symbol mean?

It's the official Japanese postal code marker, derived from the katakana テ (te) for "Teishin" — the old Ministry of Communications that ran Japan's postal system before 1949.

Q4: Where do I find the postal code for a Japanese address?

Use the official Japan Post search at japanpost.jp/zipcode/, or free English-friendly tools like [Japan Postal Code Lookup at yamada-tools.jp](https://yamada-tools.jp/en/utility/postal-code-lookup). Both let you search by address (Japanese or partial Romaji) to find the postal code.

Q5: How is a Japanese address structured?

Largest to smallest: postal code → prefecture (都道府県) → city/ward (市/区) → town (町) → block (丁目) → lot (番地) → building/room. Western addresses run the opposite direction.

Q6: Can I write a Japanese address in English?

Yes. Japan Post accepts Romanized (Romaji) addresses for international mail. The convention is to reverse the order (smallest to largest) so it reads correctly to non-Japanese carriers. Always include "JAPAN" in caps as the last line.

Q7: What's the postal code for Tokyo?

Tokyo has no single postal code — each ward has its own range. Central Tokyo wards use codes 100-179. Specific landmarks: Imperial Palace 100-0001, Tokyo Station 100-0005, Shibuya Crossing 150-0043, Tokyo Tower 105-0011.

Q8: Are postal codes ever 5 digits in modern Japan?

No. Modern Japan Post requires 7 digits since 1998. A 5-digit code is either legacy (pre-1998) or wrong. Always verify with the current 7-digit format.

Q9: Can one postal code cover multiple towns?

Yes, especially in rural areas. The lookup tool will list all towns sharing the code. For mail delivery, include the full town name even if the postal code is shared.

Q10: Do large buildings have their own postal codes?

Yes. Many large Tokyo buildings (Skytree, Roppongi Hills, Sunshine 60) have dedicated postal codes that differ from the general area code. Use the building-specific code if known.

Q11: How current is postal code data?

Japan Post publishes updates monthly via the Ken-All CSV. Third-party tools refresh on this schedule, so most data is current within 2-4 weeks of any change. For time-sensitive mail, verify with the official Japan Post site.

Q12: What's the difference between -ku, -shi, -cho, and -mura?

• 市 (shi) = city, 50,000+ residents
• 区 (ku) = ward (Tokyo special wards OR wards within designated cities like Osaka)
• 町 (chō / machi) = town, smaller municipality or urban district
• 村 (mura) = village, smallest municipality

Q13: Do I need a postal code to ship to Japan?

Strongly recommended. DHL, FedEx, USPS, and Japan Post EMS all use the postal code to route the package to the correct regional facility. Without a valid postal code, packages get delayed.

Q14: Is there a difference between 〒 and "ZIP" symbol?

〒 is the Japan-specific postal code symbol. "ZIP" is a US Postal Service term. They serve the same function (postal code prefix) but are different symbols. On Japanese forms and addresses, you'll always see 〒.

Q15: Can I look up Japan postal codes for free?

Yes, completely free. Official Japan Post search (japanpost.jp/zipcode/) and English-friendly tools like [yamada-tools.jp postal lookup](https://yamada-tools.jp/en/utility/postal-code-lookup) are both free. The zipcloud public API is also free for developers.

15. Official Sources

• Japan Post (Japanese): https://www.post.japanpost.jp/zipcode/
• Japan Post (English): https://www.post.japanpost.jp/index_en.html
• Ken-All CSV download: https://www.post.japanpost.jp/zipcode/dl/
• zipcloud public API: https://zipcloud.ibsnet.co.jp/
• Free English postal code lookup: [yamada-tools.jp](https://yamada-tools.jp/en/utility/postal-code-lookup)

Related EasyNihon Tools

• Address Converter — convert Japanese addresses to English Romaji format
• Moving Calculator — total cost of moving in Japan
• Garbage Sorting Guide — for new arrivals figuring out their new address
• Bicycle Laws 2026 — for getting around your new neighborhood

Final note:

Japan's postal code system is one of the world's most precise — a single 7-digit code maps to a delivery district small enough for one mail carrier to walk. Combined with Japan Post's reliable last-mile delivery, this is why mail in Japan rarely gets lost, even when addresses are written in unconventional formats by foreign senders.

The two things to remember:

Everything else, the lookup tools will handle for you.

— Yamada