Cousin marriage is legal under Japanese civil law, but some restrictions apply based on degree of kinship. Here is an overview of Japan’s laws concerning marriage between cousins and prevailing cultural attitudes.

Laws Permit Cousins to Marry

The Japanese Civil Code allows marriage between biological relatives up to and including the third degree of kinship. This encompasses first cousins, who are fourth degree relatives.

Therefore, it is legal throughout Japan for first cousins to marry, without any need for genetic testing or counseling beforehand. Double cousins are likewise permitted to legally wed.

Japan’s national marriage laws place no limitations on cousin couples starting a family together. Cousins have the same marital rights as non-related couples under the Civil Code.

Regional and Religious Restrictions

However, it is important to note that some municipalities and religious sects have enacted stricter rules concerning cousin marriage. For example, Kyoto legally prohibits cousins from marrying if they share the same surname.

Some Buddhist temples prohibit their monks from facilitating cousin marriages. Shinto shrines may also refuse to host weddings between first cousins. Check relevant regulations in your specific hometown and religious affiliation.

Cultural Stigma Remains

Even though it is legal nationwide, marrying your cousin remains relatively taboo across most of Japanese society. Surveys indicate 80-90% of the Japanese public opposes cousin marriages.

Social disapproval stems primarily from the perception that romantic relationships between cousins are incestuous. There are also concerns about potential birth defects.

As a result, first cousin marriages are extremely rare, accounting for less than 0.3% of all marriages in Japan. The few cousin couples who do wed often face prejudice and isolation within their communities.

Views are Gradually Shifting

However, objections to cousin marriage are slowly declining, particularly among younger generations. One recent study found that 60% of Japanese adults under age 30 do not oppose cousins marrying.

As stigma decreases, there has been a slight increase in cousin couples coming forward publicly about their relationships and marriages. Still, changing long-held cultural views remains an uphill battle.

Government Upholds Individual Choice

The Japanese government acknowledges that marrying a blood relative does increase the chances of certain genetic diseases.

Nonetheless, it maintains that individuals have a right to make their own decisions about whom to marry. Banning cousin marriage would go too far in restricting personal freedoms, officials argue.

Japan does require genetic counseling for couples with certain high-risk conditions prior to marriage and pregnancy. But there are no counseling mandates imposed simply for being cousins.


First cousin marriage is legal nationwide in Japan, though some regions prohibit it. Despite legality, strong cultural opposition persists, with most Japanese firmly against cousins marrying. The government continues upholding personal choice amid gradual shifts in public attitudes. For now, cousins wishing to wed face an uncertain social environment