BACKGROUND: Motivational interventions are used as preventive measures in occupational health. However, existing studies primarily focus on motivation methods and not the stage of motivation-the process from extrinsic to intrinsic motivation. The treatment self-regulation questionnaire (TSRQ) can predict workers' health at each motivational stage. Accordingly, this study examined the reliability and validity of the Japanese version of the TSRQ (Diet and Exercise) in occupational health settings. METHODS: Responses of 912 workers were analyzed. In this study, the Cronbach's alphas were 0.85 for Diet and 0.84 for Exercise after excluding items with low Item-Total correlations. Regarding convergent validity, there was a weak correlation between behavior modification stages and the TSRQ. Regarding structural validity, confirmatory factor analysis was performed assuming a four-factor structure. RESULTS: The goodness-of-fit indices were: Comparative Fit Index (CFI) = 0.94, Tucker Lewis Index (TLI) = 0.92, and Root Mean Square Error of Approximation (RMSEA) = 0.07 for Diet and CFI = 0.92, TLI = 0.91, and RMSEA = 0.08 for Exercise. CONCLUSION: The Japanese version of the TSRQ has a certain degree of reliability and validity. It can measure motivation for Diet and health-related behaviors in occupational health settings. The findings of this study may serve as a basis for promoting primary and secondary prevention.