2025-03-21

International marriages are not uncommon as exchanges with foreign countries become more active. However, nationality is an issue in such cases. The nationality of the child born to the foreigner also requires attention, as laws differ depending on the country of the foreigner who married.

Nationality of a foreigner in an international marriage

If a foreigner residing in Japan marries a Japanese national, the nationality of the foreigner does not change. If the foreigner wishes to have the same nationality as his/her spouse (Japanese nationality), he/she must apply for naturalization and acquire Japanese nationality.

In this case, you will lose your existing foreign nationality. This is because so-called “dual nationality” is not recognized in Japan.

Japanese nationality in the case of international marriage

The nationality of a Japanese man who marries a foreigner also does not change. If a Japanese man wishes to change his nationality to that of his partner upon marriage, he must go through the procedures to acquire that nationality in the partner’s country.

On the other hand, for a Japanese woman married to a foreigner, the situation is quite different. In some countries, there is a provision that “the one who becomes a wife shall acquire the nationality of her husband. If married to a man from such a country, the Japanese woman will acquire the nationality of the other party upon marriage.

However, as explained earlier, Japan does not recognize “dual nationality,” so she must choose one nationality or the other.

The time limit for selection is until the Japanese woman turns 22 years old or until two years after becoming a dual citizen (getting married), whichever is later. For example, if a 21-year-old Japanese woman marries a foreigner, she has until two years after the marriage.

If the above deadline is exceeded, the Ministry of Justice will send a notice of “selection of nationality. Nevertheless, if no procedures are taken, she will lose her Japanese nationality after one month.

Nationality of children born after international marriage

The nationality of children born of an international marriage between a foreigner and a Japanese is quite complicated.

First of all, there are two types of nationality for children: “birthright” and “lineage,” which differ from country to country. The “consanguinity principle” is based on the idea that the child acquires the nationality of the country of birth, regardless of the nationality of the parents. On the other hand, “pedigree principle” is based on the idea that the child acquires the nationality of the parents regardless of the place of birth.

Furthermore, there are two types of “bloodline principle”: “paternal priority bloodline principle,” in which the child acquires the nationality of the father, and “both paternal and maternal lineage principle,” in which the child acquires the nationality of the father or the mother.

Since Japan is a “patrilineal dual lineage” country, if the father or mother is Japanese, the child acquires Japanese nationality. Therefore, it is necessary to have a clear understanding of the laws of the foreigner’s country of marriage.

If a child born of an international marriage has “dual nationality,” the child must choose which country he or she will become a citizen of by the age of 22.

Conclusion

The issue of nationality in an international marriage depends on the laws, etc., of the country in which the Japanese person married his/her partner. The same applies to the nationality of children. When marrying, the laws of the other party’s country must be thoroughly researched and procedures must be followed.