---
title: "Find postal codes by address / 住所から郵便番号"
method: GET
path: "/v1/postal-codes/search"
---

# Find postal codes by address / 住所から郵便番号

`GET /v1/postal-codes/search`

## Request

- Base URL: `https://biz.ossalt.jp`
- URL: `https://biz.ossalt.jp/v1/postal-codes/search`
- Auth: none declared

Find Japanese postal codes by prefecture, city and (optionally) part of the town name, from Japan Post data. The city must be the full municipality name (e.g. 札幌市中央区, 新宿区); the county name may be omitted. With `office_name`, searches business-specific codes (大口事業所個別番号) of businesses in that city by name instead. Returns up to 100 matches. / 都道府県・市区町村・町域（部分一致、任意）から郵便番号を探す。市区町村は正式な名前で（郡名は省いてよい）。office_name を指定すると、その市区町村の事業所の個別郵便番号を事業所名（部分一致）で探す。

## Query parameters

- `prefecture` string: Prefecture, e.g. 東京都 (optional) / 都道府県（任意）
- `city` string, required: Municipality, e.g. 新宿区 / 市区町村
- `town` string: Part of the town name, e.g. 西新宿 (optional) / 町域の一部（任意）
- `office_name` string: Part of a business name, in kanji or katakana (optional) / 事業所名の一部（任意）

## Response `200`

OK

- Answer
  - `result` object, required: The answer / 結果
  - `source` object, required: Source and verification / 出典と照合の状況
  - `as_of` string, required: Reference date in Japan time (YYYY-MM-DD) / 基準日（日本時間）
  - `notes` string[], required: Assumptions such as estimated values / 前提（見込みの値など）
  - `flags` string[], required: `flags` holds machine-readable codes: `estimated` (a value is an estimate, e.g. a future equinox day — tell the user), `unverified` (year not yet checked against Cabinet Office data — tell the user), `assumes_current_era` (a future date written in the current era — tell the user), `outside_era` (the era date given is outside that era), `weekday_mismatch`, `closed` (the company's registry record is closed — tell the user), `excluded_from_search`, `truncated`, `not_found`, `exact_match_only`, `partial`, `ambiguous`, `city_not_found`, `ambiguous_city`.

## Other responses

- `400`: Invalid parameters / 入力の誤り
- `429`: Too many requests / 呼び出しが多すぎます
- `503`: Data unavailable / データを読めない

---

[API](https://skmtc.dev/ossalt/apis/japan-business-tools.md) · [All operations](https://skmtc.dev/ossalt/apis/japan-business-tools/llms.txt) · [OpenAPI document](https://skmtc.dev/ossalt/apis/japan-business-tools/revisions/8bb72a25e175?raw)