OBJECTIVE: This study aims to evaluate the long-term impact of living in post-disaster prefabricated temporary housing on social interaction activities and mental health status. METHODS: A total of 917 adult residents in a coastal town, whose residences were destroyed by the tsunami caused by the Great East Japan Earthquake (GEJE), were enrolled for the assessment held five years after the disaster. They answered questions about their experience and consequence of living in prefabricated temporary housing after the disaster. Their present scores on five types of self-reported measures regarding the psychosocial or psychiatric status and their present and recalled social interaction activities were cross-sectionally collected. RESULTS: A total of 587 (64.0%) participants had a history of living in prefabricated temporary housing, while the other 330 (36.0%) had not. The prevalence of social interaction activities significantly decreased after the GEJE. However, the experience of living in prefabricated temporary housing did not adversely affect the subsequent social interaction activities or mental conditions of the participants five years after the disaster. CONCLUSIONS: Living in post-disaster prefabricated temporary housing may not negatively impact subsequent psychosocial conditions or social interaction activities five years later.