Purpose. The purpose of this study was to identify the stage of change of smoking cessation behavior and investigate factors associated with the stage of smoking cessation behavior according to the transtheoretical model. Methods. The participants, 297 smokers & quitters were selected by a stratified random sampling from 127 high school sophomore students in B city. Data were collected from April 6th to 16th, in 2002 using the structured self-report questionnaire. Results. The subjects were distributed in each stage of change of smoking cessation behavior: there were 46 subjects (15.5%) in precontemplation, 73 subjects (24.6%) in contemplation, 67 subjects(22.3%) in preparation, 56 subjects (18.5%) in action, 55 subjects (18.5%) in maintenance. Compared to the precontemplation and contemplation, people in preparation tended to smoke daily more and smoked for a shorter time, and as precontemplation progressed to the maintenance, past 1 year smoking cessation frequency increased and friends smoking decreased. Smoking onset age was the earliest in preparation, and the latest in maintenance. Helping relationships and self relationships are used a lot in precontemplation and also in contemplation. In preparation, self liberation and helping relationships are used a lot, in action, self liberation and helping relationships, and in maintenance, self liberation and environmental reevaluation. At each stage, the score of negative affect situation was the highest, but the one of negative affect situation, positive social situation, habitual strength, weight control decreased as precontemplation progressed to the maintenance. While the score of social pros and coping pros decreased with increasing stage, the one of cons tended to increase. Through stepwise discriminant analysis, it was found that social pros, smoking onset age, delf-libration were the most influencing powers among factors associated with the stages of smoking cessation behavior. Conclusions. This study suggested that, in developing an effective smoking cessation intervention for adolescents, all the stage of a client's cessation had to be assessed prior to applying intervention programs. In addition, the results of this study will become a pillar of smoking cessation program planning and application.