Impacts of Dual-Income Household Rate on Suicide Mortalities in Japan. Nakamoto Misaki,Nakagawa Takatoshi,Murata Masahiko,Okada Motohiro International journal of environmental research and public health To explore impact of enhancing social advancement of females in Japan, this study determined the effects of the dual-income household rate on suicide mortalities disaggregated by attributes of gender, age, and motives between 2009 and 2017 in Japan. This study analysed impact of dual-income household rate, other household-related factors (savings, liabilities and yearly incomes per household, minors and elderly rate per household), and social/employment factors (complete unemployment rate, employment rate, temporary male and female employment rates and certification rate of long-term care insurance) on suicide mortalities disaggregated by attributes of gender, age, and motives using hierarchical linear-regression model. Dual-income household rate was significantly/negatively related to suicide mortality of the working-age female population, but significantly/positively related to that of the elderly female population. Suicide mortalities of the working-age male population and the elderly male population were significantly/positively related to dual-income household rate. Male suicide mortalities caused by family-, health-, economy- and employment-related motives were significantly/positively related to dual-income household rate; however, the dual-income household rate was significantly/positively related to female suicide mortalities caused by family-, health-, economy- and school-related motives, but significantly/negatively related to suicide mortalities caused by romance-related motives. Dual-income households suppress social-isolation and develop economical/psychological independence of females, leading to reduced suicide mortality in working-age females. However, elderly and school-age populations, who are supported by the working-age female, suffer from isolation. Working-age males also suffer from inability to adapt from the traditional concept of work-life and work-family balances to the novel work-family balance concept adapted to dual-income households. These results suggest occurrence of new social/family problems in the 21st century due to vulnerability of traditional Japanese culture and life-working-family balance concepts as well as novel sociofamilial disturbances induced by declining birth rate and ageing population in Japan. 10.3390/ijerph18115670