Background: The effect of disasters on suicidality is not known. We aimed to retrospectively determine the cumulative incidence of suicidal ideation during the 3 years after the Great East Japan Earthquake among residents in temporary housing without prior suicidal ideation, as compared to the general population. Moreover, we aimed to identify the risk factors for the onset of suicidal ideation.Methods: A cross-sectional survey involving face-to-face interviews was conducted 3 years after the earthquake with adult community residents in disaster-affected areas and a control area using the World Health Organization Composite International Diagnostic Interview version 3.0. We compared the cumulative incidence of suicidal ideation between the two areas using the Cox proportional hazard model and examined risk factors for the onset of suicidal ideation using a multiple logistic regression analysis.Results: Among 1019 respondents in the disaster-affected areas, the cumulative incidence of suicidal ideation over 1, 2, and 3 years after the earthquake was 1.4%, 2.4%, and 2.8%, respectively, which was significantly higher than that in the control area. Not being married, being injured in the disaster, and poor subjective physical health were associated with the onset of suicidal ideation.Limitations: We estimated the time of onset of suicidal ideation based on the respondents' current age and selfreported onset age, which limits the accuracy of the onset timing.Conclusions: We revealed a higher incidence of suicidal ideation in temporary housing residents and identified several risk factors, which suggests the importance of developing countermeasures to prevent suicide after a disaster.