This study examined the relationship between defending behavior in bullying and the individual characteristics variables, suchas affective empathy, self-efficacy, and social responsibility. The possibility that the variable, perceived popularity, moderatethe relationship between defending behavior and three individual characteristics variables was also tested. Major findings wereas follows. First, the individual characteristics explained about 60% of differences of individual defending behavior. Second,the student level psychological characteristics such as affective empathy, self-efficacy, and social responsibility did not have asignificant influence on defending behavior. However, perceived popularity predicted defending behavior significantly. Third,the interaction terms representing the moderation effect of perceived popularity was not statistically significant. According tothe results, social status in peer group was more important variable than psychological characteristics of a student for defendingbehavior. It means that initiation of defending behavior might depend upon the social relationship, not just individual’stendency. Also, it was discovered that individual. Also, it was discovered that een defending behavior in bullying and the indivi