Recent epidemiologic research has shown that people with higher socioeconomic status (SES) (e.g., educational attainment) have better psychological health than those with lower SES. However, the psychosocial mechanisms of underlying this relationship remain unclear. To fill this gap, the current study examines the mediating effects of job demands and job resources in the relationship between educational attainment and psychological distress. The hypothesized model was tested using large data sets from two different studies: a cross-sectional study of 9,652 Japanese employees from 12 workplaces (Study 1), and a longitudinal study of 1,957 Japanese employees (Study 2). Structural equation modeling revealed that (1) educational attainment was positively related to psychological distress through job demands, (2) educational attainment was negatively related to psychological distress through job resources, and (3) educational attainment was not directly related to psychological distress. These results suggest that educational attainment has an indirect effect, rather than a direct one, on psychological distress among workers; educational attainment had both a positive and a negative relationship to psychological distress through job demands and job resources, respectively.