This study investigated the prevalence of depression by area and socio-economic status (SES). Study participants were 32,891 Japanese elderly aged 65 and over who responded to a postal survey conducted in 15 municipalities in 2003. Depression was assessed using a short version of the Geriatric Depression Scale (GDS-15). SES was measured using years of education and income adjusted for family size. After adjustment for age, illness, higher level of activities of daily living, sex, marital status, and self-rated health, depression was still significantly associated with lower SES and residential area. Further research should also examine the area effect on health.