The purpose of this study is to analyze the relationship between Isoo Abe's pacifism and his recommendation that 'weak' men be sterilized. We are here concerned with the problem of manliness in Isoo Abe.<BR>Little attention has been given to Abe's argument in the 1920s about the necessity for sterilization of the weak. However, it is important to note that Abe was a pacifist and recommender of sterilization in 1920's. In his view, sterilization and 'peace' were inseparably related; American society as 'civilization' was the model for Abe's image of a 'peaceful' society.<BR>Abe was influenced by the American birth control movement of Margaret Sanger, and by the American eugenic movement of Paul Popenoe and Eugene Gosney. Abe insisted that the nation should exclude immigration and 'improve the race (jinsyu-kairyo),' in order to maintain homogeneity of the 'race.' That is to say, he attached importance to the 'race' problem in order to obtain 'world peace.' To solve the 'race' problem, he introduced 'birth control' to the Japanese people, and sterilization was one of the most important means for his theory of 'birth control.'<BR>Abe promoted the sterilization of weak men, because he attached importance to manliness. He believed that it was possible to create an 'ideal' society which was based, like an army, on strong people who have 'strong bodies' and 'masculine spirit.'<BR>This issue of Abe's image of manliness is surely not irrelevant to the issue of manliness in America which was examined in the studies about American history. For example, Gail Bederman has argued that there is a strong connection between ideas of 'civilization' and 'race' and the construction of manliness in America, and therefore it is not at all strange that one of the Japanese intellectuals who had been influenced by American culture also drew a connection between the notion of manliness and 'civilization' and 'race.' Further we can identify intellectual influences of this stream of thought on the international eugenic movement that includes the problem of eugenics of Nazism.