The purpose of this research was to clarify how aggression was related to social skills, and to get some clues to preventive measures against occurrence of bullying phenomena at high school. At the beginning of this research, we inquired into mutual relations between aggression and social skills of 1425 high school students (780 boys and 645 girls). As a result, a great difference by sex was not seen on the whole of aggression though boys were higher than girls in physical aggression and linguistic one and girls were higher in impatience and hostility. At the same time, we found that the higher aggression was, the lower the level of social skills was, and vice versa. That is, without regard to sex, it is important to enhance the level of social skills in order to decrease aggression. Therefore, we have to do so as a preventive measure against occurrence of bullying phenomena at high school through our educational activities. It is a pressing need to establish a concrete support strategy for that right now.
