The purpose of this study is to conduct a historical investigation to clarify how an ethos in the Japanese student baseball society was established. Most of the previous research focused on the process of how the organization of Japanese student baseball has been constructed. The results from these studies may contribute to the organization of Japanese student baseball society. However, in the process of the establishment of the Japanese student baseball organization, an ethos ingrained in this society in the game of baseball, which was introduced in the 1870's and has become one of the most popular sports in Japan, has involved not only wholesome spirituality, but also unwholesome spirituality. After defeat in World War Ⅱ, the CIE (Civil I...