The purpose of this study is to validate the mediating effects of anger expression types for anxiety on the violent behaviors of adolescent school violence offenders. For the purpose of this study, 114 adolescent school violence offenders and 178 general youths were selected. Through the structural equation model, the mediating effects of anger expression types that are manifested in the path of violent acts of adolescent school violence offenders and general youths are verified. The major findings of this study are as follows. First, for both groups, the same path of violent behavior through anger-in and anger-out was followed: youths repress anger when they have higher anxiety, and when too much anger is repressed, anger-out increases, which results in more violent behaviors. Second, the level of anxiety of adolescent school violence offenders has direct effect on the responsive violent behaviors while the level of anxiety of general youths does not have direct effect on violent behaviors. Third, although the anxiety of adolescent school violence offenders may increase violent behaviors through the paths of acting-in and acting-out, violent behaviors can be reduced by reducing anger-out. Therefore, to reduce the violent behaviors of adolescent school violence offenders, intervention is needed for those who repress their anger due to anxiety; professional education is also required for adolescent school violence offenders to help them control their anger.