In order to investigate the relationship between health practices, various psychosocial factors, and mental health, a survey was conducted by means of a self-rating questionnaire on 424 industrial workers. The questionnaire included items concerning Goldberg's 12 selected items from the Japanese version of the General Health Questionnaire, the Type A scale used in the Framingham study, Breslow's 7 health practices, and other original psychosocial, health practicing items. A total of 391 or 92.2% responded to the questionnaire. Among them, 354 (266 males and 88 females) complete responders to the GHQ were analysed for the present study. As a result, several factors such as decrease in age, perceived present illness, worsening of perceived health status, increase in anxiety concerning health, exacerbation of alcohol and smoking related behaviour, decrease in physical exercise, reduction of Breslow's 7 health practices, perceived stress and difficulty in dealing with stress, increase in stress content, negative and malfunctional coping strategies, and decrease in relaxation were, according to the GHQ scores, related to negative mental health. Furthermore, Type A scores were significantly correlated to GHQ scores, the number of stress factors, and Breslow's 7 health practices in males, but they were weak or had no correlation in females. It is considered that favorable health practices and attitudes towards health might help to maintain positive mental health, but further analysis is needed to determine their causal relationships because of the cross-sectional design of the present study.