The purpose of this study was to examine the mediating effects of mentalization, supervision, and educational analysis on the relationship between counselor’s traumatic experience and counselor’s self-efficacy. In order to verify this, we conducted a self-report survey of 178 counselors nationwide. Counselor’s self-efficacy scale, Traumatic Event Questionnaire-Revised, Self-Rated Mentalization Questionnaire, Supervision satisfaction scale, and Counselor’s educational analysis outcome scale were used to measure each variables. The main results of this study are summarized as follows: First, the higher the experience of trauma, the more self - efficacy of counselor. Second, the traumatic experience was negatively correlated with mentalization, and when the mentalization was improved, it served as a protective factor in crisis situations and positively correlated with self - efficacy. Third, the counselor s trauma experience showed negative correlations with the satisfaction of supervision, and the effect of education analysis, mentalization, satisfaction of supervision, and educational analysis effect were significantly correlated respectively. Traumatic experience can reduce the satisfaction of supervision. But after supervision, the effect of education analysis is improved and mentalization is enhanced. Finally, it positively affected the self - efficacy. The results of this study suggest that mentalization is a mediating variable in the effects of counselor’s traumatic experience on counselor’s self-efficacy. Finally, the limitations of this study were discussed.