This study was conducted to identify the related factors of cancer preventive behaviors for adolescent smokers. Data were collected from September 1st 2012 to March 31st 2013 of 200 adolescent smokers who were participating in smoking cessation school at W hospital in B city. As a results, there were significant differences in cancer preventive behaviors by grade, religion, benefit, barrier, perceived health status, daily living, alcohol, exercise, nicotine dependency, first smoking age, smoking duration and non-smoking intention. Cancer preventive behaviors were weakly negative related to knowledge about cancer, And there is weakly positive correlation between cancer preventive behaviors and attitude about cancer. Meaningful variables which explain cancer preventive behaviors were daily living, barrier, grade, exercise, benefit, knowledge about cancer, smoking cessation intention in order. Total explanation power was 30.6% and daily living has most explanation power. In conclusion, It is necessary to encourage sound hobbies and exercise instead of smoking for adolescent smokers in their daily living. And health education programmes, based on the grade and smoking cessation intention of adolescent smokers, need to be developed to emphasize the benefit of cancer preventive behaviors, and to decrease barriers against those behaviors.