This study was attempted to clarify the process of the formation of ego-ideal in adolescence. A questionnaire inquiring into real- and ideal-self images, peer image, self esteem, and self-acceptance was conducted on 158 male subjects of three age groups: junior and senior high school, and college students. Results were as follows: 1) there were no significant age differences in the correlation between ‘real self’ - ‘ideal self’ discrepancy and self-acceptance, and in the correlation between self esteem and self-acceptance ; 2) correlation between ‘real self’ - ‘ideal self’ discrepancy and self esteem was higher in college students than in other two younger groups ; 3) whereas significantly high correlation was found between ideal self and peer image in junior high school students, and between real self and ideal self in the older groups. It was thus concluded that, in early adolescence, the peer image one holds is introjected into one's ideal self image so that one's ego-ideal is consolidated then enabling one to have self esteem based on ‘real self’ - ‘ideal self’ discrepancy in late adolescence.