In several studies of patients with type 2 diabetes mellitus, a positive association between depressive symptoms and erectile dysfunction (ED) has been reported. No evidence exists, however, regarding the association between depressive symptoms and ED among Japanese patients with type 2 diabetes mellitus. Thus, we examined this issue among Japanese patients with type 2 diabetes mellitus. Study subjects were 469 male Japanese patients with type 2 diabetes mellitus, aged 19 years or over. ED, moderate to severe ED and severe ED were defined as present when a subject had a Sexual Health Inventory for Men score <22, <12 and <8, respectively. Depressive symptoms were defined as present when a subject had a Self-Rating Depression Scale (SDS) score >49. Adjustment was made for age, body mass index, waist, duration of type 2 diabetes, current smoking, current drinking, hypertension, dyslipidemia, coronary artery disease, stroke, glycated hemoglobin and diabetic neuropathy. The prevalence values of depressive symptoms, moderate to severe ED and severe ED were 15.1%, 64.2% and 51.0%, respectively. Depressive symptoms were independently positively associated with moderate to severe ED and severe ED (adjusted odds ratios were 2.23 (95% confidence interval (CI): 1.17-4.43) and 1.86 (95% CI: 1.04-3.41), respectively). In Japanese patients with type 2 diabetes mellitus, depressive symptoms may be associated with ED.