This study on novels written by Kim Dong-in, Yeom Sang-seob, and No Ja-yeong in the early 1920s, considered how sexual modernity had been formulated and defined to provide the basic form of daily experiences in modernization project. We put an comparative analysis on three writers` works, centering on the view about divorce and chastity which was essential issue of sexual modernity in 1920s. In 1920s, Kim Dong-in and Yeom Sang-seob contributed in dividing modern subject into two and formulating modern patriarchy, through sexual modernity. That is, Kim Dong-in became conscious that it was not until failing to achieve the unity of body and soul in love that he could get over egocentrism. Although he realized the ethics of the others and the ethics of family, it was just unisexual that it could be obtained only through self-awakening of male. And Yeom Sang-seob, emphasizing cultural education and self-awakening, kept negative view on sexuality and ecstasy. But he showed the power system of patriarchy completely in the point that he objectified women and subordinating them to modern patriarchy through chastity discourse. In contrast, No Ja-yeong suggests new chastity to pursue the divinity of self-pleasure from a liberalistic point of view, intend to pursue romantic love thoroughly, claim divorce for self-realization, and care for the chastity with lover. While she kept romantic view on sex, her egocentrism showed the limitation to make reality just pleasure. In short, divorce and chastity in these three writers` works show a variety of sexual modernity at the time when male-dominated modern patriarchy was systemized in 1920s. It should be noted here that Kim Dong-in and Yeom Sang-sub didn`t show conversational relation about sex listening to women`s voice but one-sided self-monologue and representation, while No Ja-yeong tried to keep conversational relation listening to women`s voice. As No Ja-yeong, however, was regarded as a popular writer and neglected from Korean literary history, also neglected was sexual modernity based on the view of equality of both sexes.