Corporate Law- View allLast updated: 2026-03-303 min readLawyer-Reviewed

Personal Data Breach Notification in Japan: APPI Obligations and Response Procedures

Key Takeaways

  • The 2022 APPI mandates breach notification: a preliminary report to the PPC "promptly" (guideline: 3–5 days) and a full report within 30 days
  • Triggers include unauthorized access, leakage of sensitive data, or leakage affecting 1,000+ individuals
  • Individual notification is also required in principle; substitutes (website posting, etc.) are allowed when direct notification is impracticable
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Mandatory Breach Notification under the 2022 APPI

The amended APPI (effective April 2022) made it mandatory to report personal data breaches to the Personal Information Protection Commission (PPC) and notify affected individuals (Article 26).

Previously a best-efforts obligation, it is now a legal duty. Violations trigger administrative orders (Article 145) → criminal penalties (Article 173: up to 1 year imprisonment or ¥1 million fine).

Reportable Incidents

Not every breach triggers a notification obligation. Four categories are covered (Enforcement Regulations, Article 7):

CategoryExamples
Sensitive personal information leakedHealth info, criminal records, disability info, etc.
Suspected improper motiveUnauthorized access, internal misconduct
Unauthorized access-relatedCyberattacks, unauthorized logins
Large-scale (1,000+ individuals)Large database leaks

Note: Even accidental incidents (misdirected emails, lost devices) trigger reporting if they fall into these categories.

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Reporting Timeline and Content

Preliminary Report (First Report)

Submit promptly after learning of the breach — the PPC guideline indicates approximately 3–5 days.

Minimum content: - Outline of the incident - Categories of personal data affected - Estimated number of individuals - Known circumstances of the incident - Current response status

Final Report

Submit within 30 days of the preliminary report (or 60 days for unauthorized access incidents).

Final report content: - Date/time of breach occurrence and discovery - Categories and confirmed count of affected individuals - Cause of the breach - Secondary damage risk and prevention measures - Status of individual notification - Recurrence prevention measures

Individual Notification Obligation

Notification to affected individuals is also required in principle (Article 26(2)).

Method: Individual notification (email, written notice) is the default.

Substitute Measures When Direct Notification Is Impracticable

Alternatives (website posting, press release) are permitted when: - Contact information for affected individuals is unknown - Notification would interfere with the investigation

Practical Points

Uncertain Breach Count

At the preliminary report stage, estimates are acceptable. Confirm accurate figures in the final report.

Breach at a Data Processor (Vendor)

When a subcontractor/processor experiences a breach, the data controller (principal) bears the reporting obligation (related to Article 24 supervision duties).

Establish a system for receiving prompt breach reports from vendors.

Intra-Group Leaks

Even transfers within a corporate group — if between separate legal entities — may trigger reporting.

Internal Response Framework

Recommended preparation:

MeasureContent
Incident response policyClear flow: detect → report → respond
Internal reporting channelEasy for employees to report incidents
Response teamSecurity, legal, and management coordination
Evidence preservationLog retention and anti-tampering procedures
Regular drillsAt least annual incident response exercises

Summary

The 2022 APPI established clear breach notification obligations: preliminary report within 3–5 days, final report within 30 days (60 for unauthorized access). Preparing an incident response policy and designated team in advance is essential for meeting these tight deadlines.

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This article provides general legal information and does not constitute legal advice. For specific legal issues, please consult with a qualified attorney.

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