In December 2012, a high school student, a member of basketball club, committed suicide because of corporal punishments by his teacher. This gave a great shock to not only the academic world of sports science but also the whole Japanese society. Associations made statements to get rid of corporal punishments. It has been pointed out, however, that corporal punishments are not present - day problems and have been a dangerous issue since long ago. Furthermore, in Japan, acts of violence among players in sports groups occurred over and over as well as corporal punishments. These show that sports groups in Japan have violent nature. Media made a great fuss and ostensible right or wrong arguments were repeated when acts of violence occur. But, problems of violence are not solved at all. Why? It is because violent phenomena occur in daily human relationships, which are not distinguished completely from abnormal ones. This paper clarifies the nature of sports groups in Japan and its relation to the violent phenomena. We reveal the fundamental structure of human relationships in sports groups and explore the moment of violent phenomena in its structure by focusing on arguments of Sigmund Freud, Rene Girard and Takeo Doi. Keywords of Freud's group psychology are being in loved and identification. Freud's group psychology is a kind of social philosophy and describes collapse of the ego of members. The keyword of Girard's theory is triangle desire. According to Girard, triangle desire describes a situation that people are in a state of confrontation which occurs by imitative desire. Their arguments will be a clue to excavate the moment of violent phenomena in usual human relationships. Moreover, these keywords can be related to amae which plays an important role in Doi's theory on Japanese culture and human relationships. We can grasp the nature of sports groups in Japan and its relation to violent phenomena with Doi's notion of amae.