The purpose of this study was to investigate the exercise psychosocial factors, body image and regular exercise behavior of the junior high school students in Taipei, and to explore the correlates of demographic characteristics, exercise psychosocial variable and body image variable in relation to regular exercise behavior. By using a stratified cluster sampling method, 377 valid samples(response rate 98.95%)of the seventh and eighth grade students in Taipei were surveyed with a self-administered questionnaire. Data were analyzed with t test, chi-square test and logistic regression. The main results of this research were summarized as follows: 1.59.9% of the subjects did regular exercise. Male’s regular exercise rate was higher than female’s. 2.The subject’s perceived self-efficacy for exercise and exercise social support were in lower level, perceived benefits for exercise and sport enjoyment were in higher level, and perceived barriers for exercise were in average level. 3.According to the body image questionnaire, the level of the subject’s body-image was above average. Among the seven categories of factors on the questionnaire , health orientation is the most positive one, and appearance evaluation is the most negative one. 4.Self-efficacy for exercise, perceived benefits for exercise, exercise social support and sport enjoyment of the subjects with regular exercise were higher than those of the subjects with no regular exercise. On the other hand, the perceived barriers for exercise of the subjects without regular exercise were higher than that of the subjects with regular exercise. 5.The body image of the subjects with regular exercise was higher than that of the subjects without regular exercise, as shown in the following categories: appearance, physical and health evaluated, physical orientation, health orientation and body areas satisfaction. Female students’ concerns about the appearance were associated with regular exercise. Male students’ evaluations of their own appearance, health, and body areas satisfaction were positively correlated with regular exercise. 6.Physical orientation, perceived self-efficacy for exercise and perceived benefits for exercise were significant predictors of regular exercise behavior. Male students’ most important predictor of regular exercise was perceived self-efficacy. However, the number of home sport equipment and health orientation were the important factors of regular exercise behavior for female students. Based on these results, it was suggested that enhancing perceived self-efficacy for exercise and exercise social support, eliminating perceived barriers for exercise, and attaching importance to male and female exercise differences, and the design of Health and Physical Education courses, all these should be done to develop the positive body image and the regular exercise behavior of junior high school students.