Hattoushin (a 1:8 head:body length ratio) represents a distinctive way of defining female physical beauty. Discourse on this topic in Japan appeared during the postwar reconstruction period, sometimes referred to as "the age of the physical body," as a representation of the ideal female physical image, and it continues to resonate with Japanese women today.<br> This paper takes up the notion of hattoushin and addresses the following issues using Butler's genealogical method for gender: ① What were the social contexts in which it emerged, and ② what techniques of body modification did it generate? ③ With a particular focus on female PE, in which the pursuit of physical beauty was incorporated, the position of PE as an essential element for femininity is explored. The aim of the present paper is to clarify how females and/or femininity were defined in terms of physical traits.<br> The results are as follows.<br> ① The emergence of hattoushin was due to the appearance and rise of fashion modeling as a profession, and ofMs. Kinuko Ito winning third place in the Miss Universe contest. However, the popularity of hattoushin was not merely because it came to be used as a description of the body. It was recognized as a well-developed "health andbeauty" movement that could overcome the negative aspects of defeat/occupation and was regarded as a symbol of postwar female liberation.<br> ② As a result of this rising attention to the female body form, hattoushin was recognized as the ideal that could be achieved through new techniques such as cosmetic gymnastics and "physical standard values" for visualizing ideal physical beauty.<br> ③ Postwar female PE reform had a particularly strong influence on the development of female physical beautyculture, aiming to establish the independence of females under the slogan "Female PE with female hands". Inthat process, the pursuit of physical beauty through cosmetic gymnastics took a central role. Female PE reformdeveloped because postwar feminism itself evaluated the pursuit of physical beauty as a medium for subjectiveself-expression by women who were liberated.<br> This process is similar to Butler's statement "The feminist subject turns out to be discursively constituted by the very political system that is supposed to facilitate its emancipation". That is, female PE itself, which is a feminist political system promoting female liberation, decided on an ideal form of femininity, and thus strengthened "female" categorization. More specifically, feminism itself called for the pursuit of physical beauty, and inspired many women.