Japanese Phone Number Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching japanese phone number, 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 Phone Number
# ReDoS-safe | RegexVault — Localization > Phone Numbers

import re

japanese_phone_number_pattern = re.compile(r'^(?:(?:\+81[\s.-]?|0)(?!0)(?=[0-9\s.-]{10,13}$)(?:[1-9][0-9]{0,3}[\s.-]?[0-9]{2,4}[\s.-]?[0-9]{4})|(?:\+81[\s.-]?|0)(?!0)(?:[1-9][0-9]{3}[\s.-]?[0-9]{1,2}[\s.-]?[0-9]{4}))$')

def validate_japanese_phone_number(value: str) -> bool:
    return bool(japanese_phone_number_pattern.fullmatch(value))

# Example
print(validate_japanese_phone_number("+81 3 1234 5678"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Phone Numbers 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

Japanese area codes: 03 (Tokyo), 06 (Osaka), 011 (Sapporo). Mobile numbers start with 070, 080, 090 (in domestic format). IP phone (050). +81 replaces the leading 0. Total 10-11 digits.