The purpose of this research was to investigate occupational stress and its related factors among university teachers in Japan. Questionnaire surveys were mailed to 924 university teachers in Japan with a response rate of 43.8%, N = 405. The General Health Questionnaire 28 (GHQ-28), Multidimensional Scale of Perceived Social Support (MSPSS), short Japanese version of brief Coping Orientation to Problems Experienced (COPE) and the Work Situation Questionnaires (WSQ) developed by the authors were administered to participants. Results indicated that university teachers had some mental health problems in relation to gender, professional position, conditions of taking paid leave, job satisfaction, job control, social support, and coping skills. These findings provide evidence that in order to improve the mental health of university, teachers need to take their paid leave freely. It is important to keep high their job satisfaction levels, job control levels, and social support. The results also indicated that the ineffective coping styles lead to poor mental health. In addition, the findings identified the necessity for support of female teachers and younger lecturers, who had a greater tendency toward poor mental health.