As the prevalence of depression among adult men has been increasing over time, a longitudinal approach is necessary to understand more deeply how adult men’s depression prevalence has been changing and what indicators influence their levels of depression over time. This study examines how employment status affects adult men’s depression and investigates an interaction effect of education level on the relationship between employment and depression. The current study employed the National Longitudinal Survey of Youth 1979 for Children and Young Adults. Using eleven waves of data, a total of 999 adult men were selected for the final sample. The current study used a Random Effects Model (REM). Employment and educational attainment significantly affected adult men’s levels of depression over time. Educational attainment moderated the relationship between adult men’s employment and depression levels over time. Long-term social services to help unemployed adult men should focus on improving adult men’s skills and opportunities to have stable employment, leading them to have lower levels of depression over time. More opportunities for higher education should also be provided to adult men of all ages. Opportunities for unemployed men without higher education to improve their educational attainment may also help to lower their rates of depression over time.