Japan Revises Imperial Law to Keep Married Women in Royal Family

The legislation is intended to address the declining number of royal family members.

Under the revised law, a male child born to an adopted member of a former imperial family branch would be eligible to succeed to the Chrysanthemum Throne.

However, these provisions had not been discussed at plenary meetings involving representatives of the ruling and opposition parties. Opposition parties, including the Constitutional Democratic Party of Japan, strongly objected, arguing that the legislation did not represent a consensus of the Diet.

The bill was approved at a plenary session of the House of Councillors with support from the ruling parties, the Democratic Party for the People, Komeito and others.

The Constitutional Democratic Party, the Japanese Communist Party and Reiwa Shinsengumi voted against the legislation.

Japan’s Imperial House Law dates to the Meiji era, when the first modern rules governing the monarchy were established in 1889. The law formalized succession through the male line, limiting eligibility for the throne to male descendants of emperors through their fathers. Although Japan has had eight reigning empresses, the traditional position has been that they served without creating a new maternal line of succession.

A new Imperial House Law took effect alongside Japan’s postwar Constitution in May 1947. Unlike the prewar law, which had a status comparable to the Meiji Constitution, the postwar legislation became an ordinary law subject to approval and revision by the Diet. It retained male-line, male-only succession while defining membership of the Imperial Family and regulating marriage, regency and other institutional matters.

The postwar restructuring sharply reduced the size of the Imperial Family. In October 1947, 51 members of 11 collateral branches lost their imperial status and became private citizens, partly to reduce the financial burden of maintaining a large royal household. The remaining family was largely confined to Emperor Hirohito’s immediate relatives and the households of his brothers.

The law also stipulated that a female member of the Imperial Family must leave the household when she marries someone outside it. This rule gradually reduced the number of working royals because imperial princesses became private citizens upon marriage, while their husbands and children did not enter the Imperial Family. Former Princess Mako, who left the family after marrying Kei Komuro in 2021, became one of the most prominent recent examples.

Concern over the future of the monarchy intensified because the family produced few male heirs. The birth of Prince Hisahito in 2006 temporarily eased the succession problem, but the throne remained restricted to a very small number of men. Debate therefore developed along two related but distinct lines: how to maintain enough royal family members to carry out official duties, and whether the succession rules themselves should be changed.

A government advisory panel in 2005 recommended allowing women and their descendants to inherit the throne, which could have opened the way for Emperor Naruhito’s daughter, Princess Aiko, to become emperor. The proposal lost momentum after Hisahito’s birth, and conservative lawmakers continued to argue that succession through an unbroken paternal line was central to the monarchy’s legitimacy.

The issue returned to the political agenda following the 2017 legislation that permitted Emperor Akihito to abdicate. An accompanying parliamentary resolution called on the government to consider measures for securing stable imperial succession and addressing the declining number of royal family members. Subsequent discussions concentrated on allowing princesses to retain their status after marriage and admitting male-line descendants of the former imperial branches through adoption.

The revised law is intended primarily to preserve the size and functioning of the Imperial Family without immediately changing the male-only succession system. Allowing married female royals to remain in the family prevents the automatic loss of experienced members who perform ceremonies, attend public events and represent Japan overseas.

The adoption provision serves a different purpose. It creates a route for male-line descendants of the 11 former imperial branches to return to the Imperial Household, potentially expanding the pool of male family members. Under the revision, an adopted man would not automatically become eligible for the throne, but a son born after his entry into the Imperial Family could possess succession rights.

Supporters view the combination as a compromise that addresses the shortage of royals while preserving male-line succession. Critics argue that it avoids the central question of whether women, particularly Princess Aiko, should be allowed to inherit the throne. Opposition parties also objected that some of the final provisions had not been fully discussed at the multiparty meetings intended to establish a consensus across the Diet.

The revision therefore represents the most significant attempt in decades to reshape the Imperial Household, but it does not resolve the broader succession debate. It allows women to continue serving as royal family members after marriage while relying on descendants of former male-line branches to provide possible future heirs.

Source: TBS