Background: The case of bullying in schools has increasingly become a phenomenon that is spreading in the world and has a negative impact on the school atmosphere in creating a good learning environment without fear. Educational institutions have the task of creating and guaranteeing a conducive and safe learning atmosphere so that students feel happy and at ease while at school. This can be supported by teachers who have good knowledge, attitudes and self-efficacy towards bullying cases. Objective: To find out the effectiveness of anti-bullying education on teacher's knowledge, attitudes and self-efficacy atJunior High School of 11 Yogyakarta. Method: The method used a quasi-experimental approach. The population in this study amounted to 23 teachers at junior High School of 11 Yogyakarta. The sampling technique in this study was a total sampling of 23 teachers and using paired t test. Results: Knowledge prior to the intervention of the average respondent was in the good category, good enough attitude and self-efficacy with the less good category. Knowledge after being given an intervention is mostly in the good category, being good and good self efficacy. The statistic test shows that anti-bullying education is effective on the knowledge, attitudes and selfefficacy of teachers at junior High School of 11 Yogyakarta. Conclusion: Anti-bullying education is effective on the knowledge, attitudes, and self-efficacy of teachers atJunior High School of 11 Yogyakarta.