The purpose of this study was to examine psychological characteristics associated with bullying such as interpersonal relationship dispositions and the fear of the negative evaluation in middle school students that play different roles in bullying(a bystander, a defender, a bully-follower, a bully, a victim) as well as those associated with willingness to seek help in bullying. A total of 543 middle school students in Daegu participated in the study and they completed questionnaires assessing interpersonal relationship dispositions(KIAS) and the fear of negative evaluation (FNE). Participant Role Questionnaire(PRQ) was used to categorize students according to their type of involvement in bullying. Major findings are the following. First, bullying was related to interpersonal disposition. Bystanders are characterized by warm/agreeable, while defenders by ambitious/dominant, warm/agreeable and gregarious/extraverted. Bully-follower did not show any distinct characteristics. Bullies were notably characterized by ambitious /dominant and arrogant/calculating. Finally, victims were characterized by cold/quarrelsome, aloof/introverted and lazy/submissive. Second, the examination of the fear of negative evaluation according to the type of involvement in bullying showed that the fear of negative evaluation was scored the highest in the victim group and the lowest in the defender group. Third, regarding the willingness to seek help, defenders showed a greater willingness to seek help. Fourth, the willingness to seek help was negatively associated with the fear of negative evaluation and aggressive attitudes. Fifth, the interpersonal characteristics of cold/quarrelsome, aloof/introverted were negatively correlated with the willingness seek for help, while ambitious/dominant, unassuming/ingenuous, warm/agreeable and gregarious/extraverted were found positively correlated with the willingness to seek help. Current findings suggest that to effectively address the problem of bullying in school, it will be necessary to include all those involved in bullying, not just victims or bullies, developing tailored interventions that takes into consideration of the different roles assumed by each student in bullying. Such intervention might benefit from consideration of interpersonal disposition of each participant role and fear of negative evaluation by others.