Purpose: The purpose of this study was to investigate the state and factors associated with level of physical activity and exercise in adolescents. Method: The subjects in this study included 528 adolescents registered at two junior high schools and two senior high schools in J City. The data were collected between October 20 and 30, 2006. Result: The study results showed that 23.8% of the adolescents engaged in vigorous activities for at least 20 minutes, three times a week, while 3.8% of the adolescents participated in moderate activities for at least 30 minutes, five times a week. The subjective level of health was determined to be $3.51pm.91$ points on a 5-point scale. The level of stress was $2.58pm.83$ points on a 4-point scale. The obesity index was $4.26pm20.84$ points. Significant correlations were found between the subjective level of health and level of stress (r=-.201, p=.000), the subjective level of health and the obesity index (r=-.135, p=.004), and between the level of stress and the obesity index (r=.107, p=.024). Conclusion: These results showed that developing a health promotion program that includes an exercise program specific to gender and level of education, individualized strategies of stress control and optimal weight control is required.