Purpose: The purpose of this study was to investigate the Enneagram personality types, ego-identity, self-efficacy and interpersonal relations among adolescents in high school. Methods: The participants were 322 high school students. Data were collected through self-report questionnaires, which were constructed to include demographic-environmental factors, Enneagram personality types, ego-identity, self-efficacy and interpersonal relations. The data were analyzed using descriptive statistics and pearson correlation coefficients. Results: In the nine Enneagram personality types, type 9 was highly measured. In the triadic center of Enneagram personality types, gut type was highly measured. In the wing, 9W1 was highly measured and the disruption rather than integration was highly measured. The most development level was level 5. The score of ego-identity was 3.25, the score of self-efficacy was 3.32 and the score of interpersonal ralations was 3.50. The correlation of ego-identity, self-efficacy and interpersonal relations showed significantly positive correlation with all. Conclusion: There were correlating relationships among ego-identity, self-efficacy, interpersonal relations in high school students. Based on the outcomes of this study, it is necessary to study on the relationship between Enneagram personality types and related variables. Also, We need to develop program that improve ego-identity, self-efficacy and interpersonal relations according to Enneagram personality types.