OBJECTIVES: Treatment disparity by gender and age among patients with depressive disorder in working population has not been examined in Japan. This study examined treatment disparity by gender and age among patients newly diagnosed with depressive disorder based on the claims database of health insurance societies between 2008 and 2011 in Japan. METHODS: Retrospective cohort database (N=600,000) was followed up for four years to identify patients (18 ≤ age ≤ 65) with newly diagnosed depressive disorder. The patients were followed up for one year after the index date (the first date of diagnosis). Psychotropic drugs used to treat depressive disorder included first- and/or second-generation antidepressant, benzodiazepine, sulpiride, and antipsychotics. The treatment duration and time to treatment by gender and age were evaluated by Cox regression model. RESULTS: A total of 5,464 patients (men: 3,483, mean age: 36.1±9.9) with depressive disorder was identified. Median treatment duration was 123 days (men: 150 days, women 92 days). 90.1% of patients was prescribed at least one psychotropic drug within 30 days from the first date of diagnosis (84.5% in women and 93.1% in men). The proportion of patients who were prescribed at least one  psychotropic drug for the first time after 6 months from the index date was 5.6% (men: 3.8%, women: 9.1%). The result showed that older patients were more likely to be treated longer period. In addition, men tend to be prescribed at least one psychotropic drug in a shorter period of time from the index date compared to that in women. CONCLUSIONS: This study suggested the trend of treatment disparity between men and women as well as age in working population with regard to treatment duration and time to prescription. Further study is needed for generalizability.