The purpose of this study is to investigate the cause of the juvenile sexual offense. To fulfill the goal of this study, the status and transition of the juvenile sexual criminals were checked for five years statistics and the psychological growth environment, ego-identity, MMPI, etc were considered. The results were as follows: First, In accordance with the individual characteristic of the psychological growth environment, there were a great deal of differences between the two groups. Second, The juvenile criminals under probation were more positive behavior than the juvenile criminals in jail on the psychological positive factors- freedom, communication, intimacy, affection, etc. Third, The ones under probation were higher index than the ones in jail on the ego-identity of seven lower factor except the unique factor. Fourth, The interrelation of the mental health, psychological growth environment, and ego-identity, show the tendency of inadequacy that the better the psychological growth environment and ego-identity they have, the worse the mental health they are..