Objective The purpose of this study was to investigate the risk factors that influence depression among single mothers. Methods Participants were 195 single mothers and 357 married mothers living in an urban community in South Korea. All subjects completed self-report questionnaires that included the following self-rating scales: the Global Assessment of Recent Stress, the Center for Epidemiologic Studies-Depression scale, and the Korean version of the Alcohol Use Disorder Identification Test. Multiple logistic regression analysis was performed to examine independent factors affecting single mothers’ depression. Results The prevalence of depression differed notably between the single mothers and the control group, at 33% and 8%, respectively. In the single mothers, young age, low income, residential instability, high stress, and high alcohol-related problems were determined to be associated with depression. Furthermore, after adjusting for covariates, living in rental housing (OR = 11.46, 95% CI 1.72–76.46) was found to be an independent risk factor of depression in the single mothers, while stress (OR = 1.16, 95% CI 1.09–1.24) was found to have this effect on the married mothers. Conclusions Practical services concerning economic stability and parenting support should be provided for single mothers to reduce depression among this demographic.