ABSTRACT: 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.