Naturalization for Korean Nationals｜Family Register and Loss of Nationality in Practice
Introduction
Naturalization applications from Korean nationals have the longest history of any nationality group in Japan. According to Ministry of Justice statistics, approximately 370,000 people of Korean/North Korean nationality have naturalized in Japan on a cumulative basis. While the annual figure has been declining to around 2,000 in recent years, Korean nationals remain one of the major nationality groups among naturalization applicants.
This article explains the specific documents and procedures involved when Korean nationals apply for Japanese naturalization.
What Makes Korean Nationals’ Applications Different
Key Differences from Other Nationalities
| Item | Korean Characteristics |
|---|---|
| Identity documents | Korean Family Register (5 types of certificates) |
| Renunciation of nationality | Must file a loss-of-nationality report within 2 years of naturalization |
| Kanji | Relatively advantaged in reading and writing kanji |
| Document acquisition | Can be obtained at the Korean Embassy/Consulate in Japan |
| Domicile registration issues | Some applicants are unaware of their registered domicile in Korea |
Required Documents (Korea-Specific)
Korean nationals must obtain the following five types of certificates from Korea’s Family Register System (가족관계등록부).
Five Certificates from the Korean Family Register
| Certificate | Korean Name | Contents |
|---|---|---|
| Family Relationship Certificate | 가족관계증명서 | Relationship between the applicant and family members (parents, spouse, children) |
| Basic Certificate | 기본증명서 | Basic personal details: birth, marriage, death, etc. |
| Marriage Relationship Certificate | 혼인관계증명서 | Detailed information on marriage |
| Adoption Relationship Certificate | 입양관계증명서 | Information on adoption |
| Full Adoption Relationship Certificate | 친양자입양관계증명서 | Information on full/special adoption |
Important: These certificates can be obtained at the Korean Embassy or General Consulate in Japan. In many cases, certificates are required not only for the applicant but also for their parents.
Notes on Obtaining the Documents
- Request the “detailed” version — Specify「상세 (detailed)」rather than the standard version; the standard version omits certain entries
- Parents’ certificates are often required — Since naturalization applications must show the full picture of family relationships, parents’ Family Relationship Certificates and Basic Certificates may also be requested
- Confirm the registered domicile (登録基準地) — The registered domicile in Korea is needed to obtain these certificates
If the Registered Domicile Is Unknown
Some long-term residents in Japan are uncertain of their registered domicile (登録基準地) in Korea.
How to resolve this:
- Ask relatives — the most reliable approach
- Request a search for old household records (除籍謄本) through the Korean Embassy or Consulate in Japan
- Use Korea’s Supreme Court Electronic Family Register System (requires a Korean Resident Registration Number)
Document Translation
All Korean-language documents must be accompanied by a Japanese translation.
Translation Format
- Translations are written on A4 paper
- Include the translator’s name, address, signature, and date of translation
- Translate faithfully to the original — paraphrasing or summarizing is not permitted
Notes for Korean Translations
- Kanji for personal names — Korean certificates often include kanji, which should be used as written
- When kanji is not available — Write the name in katakana and include the original Korean romanization
- Place names — Korean administrative division names are transcribed directly in kanji
Renunciation of Korean Nationality
Filing a Loss-of-Nationality Report
Under Korean law, acquiring a foreign nationality causes automatic loss of Korean nationality (Article 15, Korean Nationality Act). However, unless a formal loss-of-nationality report is filed, the Korean family register will continue to record Korean nationality.
| Step | Description | Timeframe |
|---|---|---|
| 1 | Receive Japanese naturalization approval | — |
| 2 | File loss-of-nationality report at Korean Embassy/Consulate in Japan | After naturalization |
| 3 | Korea processes the loss of nationality | Approximately 1–3 months |
| 4 | Issuance of loss-of-nationality confirmation | After processing |
Documents Required for the Loss-of-Nationality Report
- Loss-of-nationality report form
- Copy of the naturalized person’s Japanese identity document
- Japanese koseki (family register) showing naturalization entry
- Korean passport (valid)
- Family Relationship Certificate
Note: The loss-of-nationality report must be filed within 2 years of naturalization approval. Failure to do so means the Korean record will not be updated, which can cause complications in the future.
Common Visa Status Paths for Korean Nationals
| Pattern | Characteristics |
|---|---|
| Special Permanent Resident | Simplified naturalization (Articles 7 and 8) often applies |
| Permanent Resident | Residency requirement already met |
| Spouse of Japanese national | Eligible for simplified naturalization |
| Engineer/Specialist in Humanities/International Services | Standard naturalization (5+ years of residence required) |
| Business Manager | Standard naturalization + additional business-related documents |
Note: For details on naturalization for Special Permanent Residents, see our separate article “Naturalization for Special Permanent Residents”.
Additional Considerations for Korean Nationals
Military Service Obligations
Korean men are subject to mandatory military service. Applicants who have not completed military service or who have been exempted must declare their status. While this does not directly affect the naturalization application itself, it may have implications for the Korean-side nationality renunciation process.
Generational Differences among Korean Residents in Japan
- First and second generation — May need to arrange documentation under Korea’s old family register system
- Third generation and beyond — Korean family register records may be incomplete or missing
- Special Permanent Residents — Naturalization conditions are significantly relaxed
Our Support
For consultations on naturalization applications, please contact Kaneko Hidetaka Gyosei-Shoshi Office.
- 98% approval rate
- Assistance with obtaining and translating the Korean Family Register
- Languages supported: Japanese · Chinese · Vietnamese
- Free initial consultation
- Serving clients nationwide, centered in Chiba and Tokyo (online consultations available)