The aim of this study is to assess the role of self-esteem as a protective factor of suicidal behavior in high school. Subjects of this study were N = 196 students (98 boys and 98 girls) from SMA Negeri 2 and SMA St Yoseph in Denpasar, with age ranged from 15 to 17 years. The Rosenberg Self-esteem Scale (1965) and the Scale of Suicide Behavior (2015) developed from the terms of suicidal behavior from Bridge, Goldstein and Brent (2006) were asked to be filled. Pearson Product Moment results showed that the correlation (R) between self-esteem and suicidal behavior is -0.250 with significance level 0.000 (P <0.005), and self-esteem variable can explain the variable of suicide behavior about 6.25%. This study proves that there is a relationship between self-esteem and suicidal behavior in adolescents, the higher the self-esteem, the lower the suicidal behavior, and vice versa. The study also shows that there is no difference in suicidal behavior between boys and girls. The implication of this research is strengthening self-esteem can reduce suicidal behavior in adolescents.