This study explored student-level variables(reactive, proactive relational aggression, gender, school level) and class-level variables(perceived teacher support, class size) that influence bullying in elementary and middle school students. Also, this study investigated a moderating effect of perceived teacher support on the relationship between reactive, proactive relational aggression of functional subtypes and bullying. For this, the multi-level path model was analyzed for 5 elementary and secondary schools, 38 classes, and 965 students (64.2% female students). Results of multi-level path model analysis including student- and class-levels, first, proactive relational aggression showed a positive effect on victimization. On the other hand, reactive relational aggression did not have a significant effect on victimization. Second, both proactive relational aggression and reactive relational aggression were found to have a positive effect on bullying. Third, the perceived teacher support of class-level variables was found to significantly moderated the relationship between the subtype of relational aggression by function and bullying. Based on the results of this study, implications and intervention strategies to prevent bullying were discussed.