The present study investigated relationships among self-management skills, communication with superiors, and the mental health of employees in a Japanese worksite. The subjects were manufacturing workers in a medium-sized company in Kyushu. In 1999, we mailed a self-administrated questionnaire which included questions on age, gender, job rank, communication with superiors, a General Self-Efficacy Scale, a Self-Management Skill Scale, and the Japanese version of the 12-item General Health Questionnaire (GHQ-12). Eighty percent of the subjects returned the questionnaire. Excluding senior managers and insufficient answers, the final response rate was fifty-five percent. The multiple regression analysis showed that job rank contributed significantly and positively and that age, communication with superiors, and self-management skills contributed significantly and negatively to the GHQ-12. Our results implied that self-management skills might have the potential of affecting the mental health of Japanese employees.