Japanese Address System Explained: From Prefecture to Block Number
Learn how Japanese addresses work, from the prefecture level down to block and building numbers. Understand why Japan uses a unique area-based system.
Why Japanese Addresses Are Different
The Japanese address system is fundamentally different from Western addressing. Instead of identifying a specific street and house number, Japanese addresses describe an area that narrows progressively from the largest administrative unit to the smallest block and building number. Understanding this system is essential for any developer building products for the Japanese market.
Japan has 47 prefectures, which are the top-level administrative divisions. They use four different suffixes:
都 (to) - Metropolis: only Tokyo (東京都)
道 (do) - Circuit: only Hokkaido (北海道)
府 (fu) - Urban prefecture: Osaka (大阪府) and Kyoto (京都府)
県 (ken) - Prefecture: the remaining 43
City (市 - shi) / Ward (区 - ku)
Large cities are divided into wards (ku). Tokyo has 23 special wards. Other major cities like Osaka, Yokohama, and Nagoya also use wards. Smaller municipalities use city (市 - shi), town (町 - machi/cho), or village (村 - mura/son).
District/Town (町 - cho/machi)
Within a city or ward, addresses reference a named district or town area.
Block and Building Number (番地 - banchi)
This is where Japanese addresses diverge most from Western systems. Instead of sequential street numbers, Japan uses:
Chome (丁目) - A numbered subdivision of a district
Ban/Banchi (番/番地) - Block number within the chome
Go (号) - Building number within the block
These are typically written as numbers separated by hyphens: **1-2-3** means Chome 1, Block 2, Building 3.
Building Name and Room Number
For apartments and office buildings, the building name and room number are added as a final line.
Japanese Postal Codes (郵便番号)
Japanese postal codes are 7 digits in the format **NNN-NNNN**, prefixed with the postal mark 〒.
〒100-0001
The first three digits identify a broad region, and the last four narrow it to a specific delivery area.
Validation Pattern
^[0-9]{3}-[0-9]{4}$
Writing Order
A critical difference: Japanese addresses are traditionally written from **largest to smallest** unit (prefecture first, building number last). This is the reverse of Western convention, which goes from smallest to largest (house number first, country last).
When writing Japanese addresses in English or for international mail, the order is sometimes reversed to match Western expectations. Your software should handle both conventions.
Tips for Developers
**Do not use a street name field** - Most Japanese addresses do not reference street names
**Support both Japanese and romanized input** - Users may enter addresses in either script
**Handle the 〒 postal symbol** - Some users include it, others do not
**Allow flexible number formatting** - Block numbers may use hyphens, dots, or Japanese characters
**Provide prefecture dropdowns** - There are exactly 47 prefectures, making a dropdown practical
**Consider right-to-left narrowing** - The address hierarchy goes from general to specific
**Test with addresses from multiple ward structures** - Tokyo's 23 wards versus smaller cities without wards