OBJECTIVES: The disaster of the Sewol ferry that sank at sea off Korea's southern coast of the Yellow Sea on April 16, 2014 was a tragedy that brought grief and despair to the whole country. The aim of this study was to evaluate the mental health effects of this disaster on the community of Ansan, where most victims and survivors resided. METHODS: The self-administered questionnaire survey was conducted 4 to 6 months after the accident using the Korean Community Health Survey system, an annual nationwide cross-sectional survey. Subjects were 7,076 adults (≥19 years) living in two victimized communities in Ansan, four control communities from Gyeonggi-do, Jindo and Haenam near the accident site. Depression, stress, somatic symptoms, anxiety, and suicidal ideation were measured using the Center for Epidemiologic Studies-Depression Scale, Brief Encounter Psychosocial Instrument, Patient Health Questionnaire-15, and Generalized Anxiety Disorder 7-Item Scale, respectively. RESULTS: The depression rate among the respondents from Ansan was 11.8%, and 18.4% reported suicidal ideation. Prevalence of other psychiatric disturbances was also higher compared with the other areas. A multiple logistic regression analysis revealed significantly higher odds ratios (ORs) in depression (1.66; 95% confidence interval [CI], 1.36 to 2.04), stress (1.37; 95% CI, 1.10 to 1.71), somatic symptoms (1.31; 95% CI, 1.08 to 1.58), anxiety (1.82; 95% CI, 1.39 to 2.39), and suicidal ideation (1.33; 95% CI, 1.13 to 1.56) compared with Gyeonggi-do. In contrast, the accident areas of Jindo and Haenam showed the lowest prevalence and ORs. CONCLUSIONS: Residents in the victimized area of Ansan had a significantly higher prevalence of psychiatric disturbances than in the control communities.