JapanWhat happens to child's surname upon divorce?
Upon divorce in Japan, a child's surname does not automatically change — it remains the surname registered at birth unless a court approves a change upon petition by a parent.
What the Law Says
Japanese law does not require or permit automatic changes to a child’s surname upon parental divorce. Any change requires formal approval by the Family Court.
Under Japanese civil law, a child’s surname is established at birth registration and remains fixed unless legally altered. Divorce between parents has no effect on the child’s registered name.
A parent may file a petition with the Family Court to change the child’s surname, but approval is discretionary and requires justification — such as serious hardship or compelling welfare reasons.
The court considers the child’s best interests, age, opinion (if mature enough), and potential impact on identity and social life.
Statutory TextA child's surname shall be the surname of the father or mother at the time of birth registration.
— Civil Code, Art. 791 — Surname of Child
Statutory TextA change of a minor's surname shall be made only with permission of the family court.
— Civil Code, Art. 791, Paragraph 2 — Change of Surname
What to Do
Confirm the child’s current registered surname in the koseki (family register).
File a petition for surname change at the competent Family Court (usually where the child resides).
Submit supporting documents: koseki copy, reason statement, child’s opinion (if age-appropriate), and evidence of welfare considerations.
Attend court hearing; the court may interview the child or appoint a guardian ad litem.
If approved, submit the court’s permission document to the municipal office to update the koseki.
Sources
Not legal advice. This article is general information based on publicly available sources, written for educational purposes. Laws change and individual situations vary. Consult a licensed attorney in your jurisdiction before acting on anything you read here. Last reviewed: 2026-06-08.