BackgroundOccupational stress among mental health nurses may affect their psychological health, resulting in reduced performance. To provide high-quality, sustainable nursing care, it is necessary to identify and control the factors associated with psychological health among mental health nurses. The purpose of this study was to examine the role of work–family conflict (WFC) in the well-known relationship between occupational stress and psychological health among mental health nurses in Japan.MethodsIn this cross-sectional study, data were gathered from 180 mental health nurses who had a coresident child or were married. Data from the Work–Family Conflict Scale, the Generic Job Stress Questionnaire, the Maslach Burnout Inventory-General Survey, and the Center for Epidemiologic Studies for Depression Scale were obtained via self-report questionnaires. The effects of occupational stress and WFC on psychological health were explored by hierarchical linear regression analysis.ResultsThe relationship between emotional exhaustion and occupational factors, including quantitative workload and the variance in workload, disappeared with the addition of WFC (each work interference with family [WIF] or family interference with work [FIW]). The relationship between emotional exhaustion and mental demands disappeared only with the addition of WIF. The relationship between depressive symptoms and variance in workload disappeared with the addition of WFC (each WIF or FIW).ConclusionOur findings may encourage hospital administrators to consider the risks of medical staff WFC. Furthermore, longitudinal investigations into the factors associated with WFC are required for administrative and psychological interventions.