Objective: To investigate the association of workplace occupational mental health (OMH) and related activities with psychological distress of workers in Japan. Methods: A total of 121 workplaces and their 3540 workers were surveyed using questionnaires assessing selected workplace OMH activities, demographic characteristics, psychological distress, and psychosocial work environment of the workers. A multilevel analysis was conducted. Results: Promotion of communication correlated significantly and negatively with psychological distress among workers after adjusting for the covariates (P < 0.01). Occupational mental health activities correlated marginally significantly and negatively with psychological distress (P = 0.06). Their moderating effect for the worker-level association between psychosocial work environment and psychological distress was not significant. Conclusions: The findings suggest that promotion of communication in the workplace is associated with reduced psychological distress among workers. In addition, OMH activities may also be useful in reducing psychological distress. Copyright © 2012 by American College of Occupational and Environmental Medicine.