In Japan, the population sex ratio has seen slight changes over the past decades. In 2021, the number of men was around **** for every 100 women, constituting a decrease from **** in 1950.

What is the sex ratio? The population sex ratio is determined by the sex ratio at birth, different mortality rates between men and women, as well as losses and gains through migration. In the absence of alteration, the sex ratio in human populations is quite constant, with only minor deviations. While the sex ratio at birth is usually *** to ***, the population sex ratio, which refers to the total number of males for every 100 females, is often below 100. The reason for the shift mostly lies in differing lifestyles and physical constitutions of men and women. In general, women tend to be more resistant to disease throughout life, while men tend to engage in higher risk behavior or violence.

Influences and consequences
The sex ratio at birth and its possible determinants such as gestation environment, climate change, chemical pollution or socio-economic factors have long been subject to scientific research. Recently the impact of natural disasters, like the nuclear disaster in Japan in 2011, was presumed to influence the sex ratio at birth. The adult gender ratio has long been recognized as a key population-level determinant of behavior. However, there are many different or competing theories in existing literature about the social impacts of gender imbalance on topics such as violence, family stability, reproduction etc.

Sex ratio at birth (male births per female births) in Japan was reported at 1.051 in 2023, according to the World Bank collection of development indicators, compiled from officially recognized sources. Japan - Sex ratio at birth (male births per female births) - actual values, historical data, forecasts and projections were sourced from the World Bank on October of 2025.

School enrollment, primary (gross), gender parity index (GPI) in Japan was reported at 1.0025 % in 2019, according to the World Bank collection of development indicators, compiled from officially recognized sources. Japan - Ratio of female to male primary enrollment - actual values, historical data, forecasts and projections were sourced from the World Bank on October of 2025.

In 2024, the overall gender gap index score in Japan reached 0.66 points, a slight increase compared to recent years. Japan ranked 118th out of 146 countries covered by the global gender gap index, placing the country far behind other G7 nations. Reasons behind Japan’s low ranking  Japan’s gender gap score in education and health indicated a closed or almost closed gender gap. However, in terms of political empowerment, Japan ranked well below the average global score, placing it among the lowest ranks within East Asia and the Pacific region. A high disparity between men and women in economic participation was another crucial reason for Japan’s poor ranking compared to other industrial nations. The low scores were mainly due to the nation’s small number of female parliamentarians, as well as a low ratio of women in managerial positions. Women in Japan Modern Japanese women enjoy more freedom, have better access to education, and have broader job opportunities compared to previous generations. Yet, traditional gender roles and male favoritism are still pervasive in Japanese culture. Japan's ongoing discussion on gender equality measures, or the lack thereof, is often highlighted in local and international media. The Japanese government currently aims to achieve a significant increase in female proportion in the political, judicial, and economic fields by the end of 2025, targeting 30 percent or more of the female share in a broad range of positions. This might fast-track the long-overdue generational change, which seems necessary to incite diversity in the country.