BackgroundDescriptive study of Japanese sexual and gender minority (SGM) population with national representativeness have not been conducted. We sought to estimate the proportion of the Japanese SGM, and to describe those demographic, socioeconomic, and health-related variables.MethodsUtilizing data on a nationwide cross-sectional internet survey from September 12th to October 19th, 2022, we conducted a comprehensive descriptive study by applying inverse probable weighting method for national representativeness. Participants self-reported as heterosexual, homosexual, bisexual, or gender minority (GM) and responded to questions on various demographic, socioeconomic, and health-related concerns.FindingsAmong Japanese adults, 4.8% identified as homosexuals, 1.3% as bisexuals, and 3.8% as GMs. SGMs were less likely to be married/partnered compared to heterosexuals, though a certain proportion were in opposite-sex marriages/partnerships. SGMs had lower household equivalent income, insurance coverage, home ownership, current smoking rates, good self-rated health, and full COVID-19 vaccination rates. They also exhibited higher rates of substance use, severe psychological distress, feelings of loneliness, and fear of COVID-19 compared to heterosexuals. When divided by assigned sex at birth, SGM males had poorer employment status, lower academic attainment, and higher body mass index compared to their heterosexual counterparts, while SGM females showed opposite trends.InterpretationDifferences in demographic, socioeconomic, and health status between heterosexuals and SGMs underscore the need for targeted health policies and interventions to address health disparities among Japanese SGMs. Additionally, these results suggest that directly applying Western health policies to the Japanese context may not always be appropriate.FundingFunded by the Japan Society for the Promotion of Science, the Research Support Program to Apply the Wisdom of the University to tackle COVID-19 Related Emergency Problems, University of Tsukuba, and Health Labour Sciences Research Grantand the Japan Agency for Medical Research and Development.