Japanese Postal Code (〒XXX-XXXX) Regex for Python

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching japanese postal code (〒xxx-xxxx), ported and verified for Python. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# Japanese Postal Code (〒XXX-XXXX)
# ReDoS-safe | RegexVault — Localization > Postal Codes

import re

japanese_postal_code_xxxxxxx_pattern = re.compile(r'^〒?([0-9]{3})-?([0-9]{4})$')

def validate_japanese_postal_code_xxxxxxx(value: str) -> bool:
    return bool(japanese_postal_code_xxxxxxx_pattern.fullmatch(value))

# Example
print(validate_japanese_postal_code_xxxxxxx("100-0001"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Postal Codes category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Capture group 1: 3-digit regional code, group 2: 4-digit local code. The 〒 symbol (postal mark) is optional in digital contexts. 100-0001 is Tokyo (Chiyoda ward). Japan Post maintains the authoritative address database.