Our office receives inquiries from Japanese nationals and their families living in Japan and overseas. Some people have obtained another country’s citizenship and wonder whether they can renew a Japanese passport. Others have children with a Japanese parent and a foreign parent and assume that dual nationality is always permitted until the child turns 20.

The answer depends on how, when and under which country’s law the foreign nationality was acquired. This article explains the general rules and why a Japanese family register or previously issued passport is not conclusive proof of a person’s current Japanese nationality.

1. Does Japan Allow Dual Nationality?

It is often said that “Japan does not allow dual citizenship.” That statement is too broad. Japanese law recognizes that a person can hold Japanese and foreign nationality at the same time in certain circumstances, especially when nationalities are acquired automatically at birth. However, Japan’s Nationality Act also establishes rules requiring the choice of nationality and provides for the loss of Japanese nationality in specified cases.

Examples of situations that may produce multiple nationality include a child who acquires Japanese nationality through a Japanese parent and foreign nationality automatically under another country’s law, or a child who acquires foreign nationality at birth based on the place of birth.

By contrast, if someone who is already Japanese later obtains foreign nationality through naturalization or an application, Article 11(1) may apply. The age of the person does not by itself remove this risk.

2. The Most Important Question: How Was the Foreign Nationality Acquired?

Do not start with the question “How old is the child?” Start by identifying the legal basis and effective date of the foreign citizenship.

A foreign country’s description of citizenship as “by descent” or “by birth” is not enough on its own. Some systems grant nationality automatically at birth; others create eligibility to apply for nationality later. The actual law and records must be examined.

3. Article 11(1): Voluntarily Acquiring Foreign Nationality

Typical examples include a Japanese national who becomes a foreign citizen through naturalization after residing overseas, or one who deliberately applies for a foreign nationality for which they are eligible.

If Article 11(1) applies, the Japanese-nationality loss occurs by operation of law when the foreign nationality is acquired. A later nationality-loss notification records the event; it is not what creates the loss. Accordingly, not submitting a Japanese notification does not necessarily preserve Japanese citizenship.

The decisive issue is whether the foreign nationality was obtained through a legally relevant voluntary acquisition process. There may be difficult questions about foreign law, the applicant’s legal representative and the nature of the registration procedure. These questions cannot be answered solely from the title printed on a foreign citizenship certificate.

4. Can a Parent’s Citizenship Application Cause a Child to Lose Japanese Nationality?

Yes, it can. A common misconception is that a minor is protected from Article 11(1) because the parent, rather than the child, completed the application. That assumption is unsafe.

A significant Tokyo District Court judgment: 17 October 2024

In a nationality-confirmation case decided on 17 October 2024, the Tokyo District Court considered a child whose adoptive parents had applied for registration as a British citizen. The court held that Article 11(1) could apply where a legal representative undertook an act seeking foreign nationality for the child and that act directly resulted in the acquisition of that nationality. The child’s claim seeking confirmation of Japanese nationality was dismissed.

The decision shows that the use of a legal representative does not, by itself, prevent application of Article 11(1). This is a district court decision concerning its particular facts, not a determination of every parent-led citizenship application or the status of any specific family.

Source: Tokyo District Court, 17 October 2024, nationality-confirmation case.

5. Examples from Russia, Portugal and Australia

Russia: a warning about nationality acquired through a parent’s procedure

The Embassy of Japan in Russia has issued guidance warning that, depending on the circumstances, a child of Japanese and Russian parentage may acquire Russian nationality through a procedure involving the legal representative rather than automatically at birth. Where the procedure constitutes voluntary acquisition, Japanese nationality may be lost under Article 11(1).

The legally important distinction is between reporting an existing citizenship and applying to acquire one. The label “birth registration” does not settle that question in every legal system.

Portugal: express warning by the Japanese Embassy

The Embassy of Japan in Portugal states in its nationality-loss guidance, dated 9 July 2025, that when a minor acquires foreign nationality through an application made by a legal representative such as a parent, the acquisition is interpreted as being by the minor’s own choice for purposes of nationality loss.

This warning concerns the legal consequences of a parent-led application; it should not be read to mean that all children of Portuguese-Japanese parentage automatically lose Japanese nationality.

Australia: “citizenship by descent” may require approval

Australia’s Australian Citizenship Act 2007 addresses citizenship by descent through an application and approval process. Under section 19, citizenship acquired through that route generally begins on the day the minister approves the application, subject to the relevant statutory conditions. That is materially different from citizenship automatically acquired at birth.

For a child born in Japan to a Japanese parent and an Australian parent, it is therefore essential to establish the exact Australian-law acquisition route and effective date before considering Article 11(1). A parent having Australian citizenship at the child’s birth does not necessarily mean the child automatically became an Australian citizen at birth.

Source: Australian Citizenship Act 2007, sections 16–19. This is a general example, not an assessment of any individual child.

6. Nationality Selection: What Do Ages 18 and 20 Really Mean?

Article 14 provides deadlines for choosing nationality for people who legally continue to hold both Japanese and foreign nationality. For those who became multiple nationals before age 18, the choice must generally be made by age 20. For those who became multiple nationals at age 18 or older, it must generally be made within two years.

These are the rules in force following the change effective 1 April 2022; transitional rules may matter for older cases.

Nor does missing the Article 14 deadline automatically mean that every person immediately loses Japanese nationality on their 20th birthday. The Nationality Act provides a notification-and-demand process under Article 15, which can lead to loss if the required action is not taken. A person who misses the selection deadline still has an obligation to address nationality selection.

What does “choosing Japanese nationality” mean?

Under Article 14(2), Japanese nationality can be chosen by renouncing the foreign nationality under that country’s law, or by making the prescribed declaration choosing Japanese nationality and stating an intention to renounce the foreign nationality. Whether that declaration also ends the foreign nationality depends on the law of the other country. Where it does not, Article 16(1) requires the person to endeavor to renounce the foreign nationality.

Accordingly, the phrases “I chose Japanese nationality,” “I no longer hold foreign citizenship,” and “Japan has recognized my status” should not be treated as interchangeable.

7. Children Born Abroad: Reservation of Japanese Nationality

Article 12 concerns a different situation: a child born outside Japan who acquires both Japanese and foreign nationality at birth. Where Article 12 applies, the child’s Japanese nationality must be reserved through the prescribed birth-notification procedure, generally within three months of birth. Without reservation, Japanese nationality is lost retroactively from birth.

This rule should not be confused with Article 11(1). Reserving Japanese nationality at birth does not create an exemption from nationality loss if the person later voluntarily acquires a new foreign nationality.

Separate statutory rules on reacquisition may be relevant to some individuals who lost nationality because it was not reserved at birth; eligibility depends on the relevant provisions and circumstances. Do not assume that these special rules apply to a loss under Article 11(1).

8. Does a Japanese Family Register or Passport Prove Current Japanese Nationality?

Not necessarily. A family register (koseki) records civil-status information, but a record remaining on file does not conclusively establish that a person has retained Japanese nationality following a legally effective nationality-loss event.

Similarly, possession of an old Japanese passport does not, by itself, resolve the question of present nationality or the passport’s validity. If Japanese nationality has been lost, passport validity and future passport applications may be affected.

Accurate declarations matter

Japanese passport procedures may require information about other nationalities and how they were acquired. Applicants should provide accurate and complete information. Knowingly false statements may have consequences under the Passport Act, depending on the facts and applicable provisions.

If you are uncertain whether you still hold Japanese nationality, do not assume that continued possession of a family register or a previously issued passport makes all travel or passport applications lawful. Seek clarification through the appropriate Japanese authorities and, where there is a legal dispute, a qualified lawyer.

Nationality loss can also have implications for immigration status if the person is living in Japan. The precise consequences depend on the person’s actual nationality status, entry history and individual circumstances. It would be inappropriate to describe every such case automatically as illegal entry, illegal stay, or a case for special permission to stay.

9. Other Ways Japanese Nationality May Be Lost

In addition to voluntary acquisition under Article 11(1), the Nationality Act includes other provisions:

• Article 11(2): choosing foreign nationality in accordance with that country’s law while already holding Japanese and foreign nationality.
• Article 12: failure to reserve Japanese nationality in qualifying foreign-birth cases.
• Article 13: voluntary renunciation of Japanese nationality through the prescribed notification.
• Article 15: possible loss following a formal demand to make a nationality choice and failure to comply within the statutory period.
• Article 16: obligations after declaration of Japanese nationality and a separate loss mechanism in specified circumstances involving foreign public office.

Effects beyond passports

Nationality may also affect the law applicable to certain family and inheritance matters. Under Japan’s Act on General Rules for Application of Laws, nationality may be one connecting factor in determining the applicable law, and Article 38 addresses the personal law of a person with multiple nationalities. However, marriage, divorce, succession and other issues each have their own choice-of-law rules. It would be inaccurate to say that every issue automatically switches to foreign law merely because Japanese nationality is lost.

10. What Should You Check Before Taking Action?

Where foreign nationality has already been acquired or is being considered for a child, the following records and questions are especially important:

1. Birth and parentage: date and country of birth; each parent’s nationality at the time of birth.
2. Foreign nationality law: whether nationality was automatic at birth or required a subsequent application and approval.
3. Application evidence: the actual forms, consent declarations, authorization documents and approval notice.
4. Effective acquisition date: the legal date foreign citizenship began, which may differ from the passport’s issuance date.
5. Japanese records: family-register entries, relevant notifications and correspondence with the municipality or Legal Affairs Bureau.
6. Authority responses: whether an official simply raised a possibility or examined the documents and explained a specific view.

For an unsettled nationality question, the Legal Affairs Bureau is an appropriate Japanese authority for nationality-related inquiries. If the issue requires contested legal interpretation, a claim against the government’s position, or court proceedings, consult a Japanese lawyer experienced in nationality law.

11. What Trust Administrative Scrivener Office Can—and Cannot—Do

If your principal question is “Have I or my child already lost Japanese nationality, and how can we contest that?”, we recommend consulting a Japanese lawyer with relevant nationality-law experience rather than booking a document-retrieval consultation.

If you need eligible Japanese civil certificates for a legitimate purpose, please read our guide to certificate retrieval and apostille services or our policy on Japanese nationality and passport-related requests. We will confirm whether a specific document service falls within our scope before accepting a request.

12. Official Laws, Guidance and Court Decision

The following are primary sources for the general rules discussed above. Foreign-nationality laws and administrative requirements can change, and each individual case requires consideration of the law applicable at the relevant time.

• Japanese Nationality Act (e-Gov Laws and Regulations Search) — especially Articles 11–16.
• Ministry of Justice: Nationality Q&A (Japanese) — nationality loss, retention, and nationality selection.
• Ministry of Justice: Choice of Nationality — procedures and deadlines.
• Embassy of Japan in Portugal: Nationality loss and renunciation — guidance dated 9 July 2025.
• Embassy of Japan in Russia: Nationality-loss guidance.
• Australian Citizenship Act 2007 — citizenship by descent, sections 16–19.

Disclaimer: This article provides general information about Japanese nationality and related procedures as of 13 October 2026. It does not constitute a determination of nationality, individualized legal advice, or representation in a legal dispute. Official authorities and courts decide matters within their jurisdiction.