This study examines (1) whether there are employment grade and gender differences in job dissatisfaction and (2) whether work, family, and personality characteristics explain grade and gender differences in job dissatisfaction. The participants were 3,812 civil servants, aged 20–65, working at a local government in Japan. In both males and females, low control, low social support, work-to-family conflict, type A behaviour pattern and negative affectivity were significantly associated with job dissatisfaction. In females, high demands, long work hours and being unmarried were also associated with job dissatisfaction. Among males, in comparison with the highest grade employees, the age-adjusted odds ratio (OR) for job dissatisfaction in the lowest grade employees was 1.90 (95% CI: 1.40–2.59). The grade differences reduced to 1.08 (0.76–1.54) after adjustment for work, family and personality characteristics. Among females, similar grade differences were observed, although the differences were not statistically significant. In comparison with males, the age-adjusted OR in females for job dissatisfaction was 1.32 (1.14–1.52). This gender difference was reduced to 0.95 (0.79–1.14) following adjustment for the other factors. The majority of employees belong to low to middle grades, and female employees have increased. Reducing grade and gender differences in work and family characteristics is needed.