This thesis aims to explore the link between women’s descriptive representation and substantive representation in the 20th National Assembly of the Republic of Korea according to the different conceptualization of women’s substantive representation. First, the link between women’s descriptive representation and substantive representation is examined by investigating whether women legislators introduce bills for women’s interests and succeed in passing such bills more than men. Plus, women legislators’ impact on the introduction of bills for women’s interests and success to pass such bills is explored separately according to different definitions of women’s interests, feminist and traditional women’s interests. This thesis also seeks to compare the influence of quota women with non-quota women on introducing bills for women’s interest and being able to pass such bills. The effect of legislators’ gender and quota women on women’s substantive representation is analyzed by running multivariate OLS regressions. The result strongly supports the positive impact of female legislators on the substantive representation of women. The regression analysis result indicates that being female is positively and significantly related to all types of women’s substantive representation, except the introduction of traditional women’s interests bills. The positive effect of the female legislators is more robust on the introduction of feminist women’s interests bills than the passage of them. However, the positive effect of the female legislators is stronger on the passage of traditional women’s interests bills than the introduction of them. When I compare the connection between women’s descriptive representation and substantive representation according to the different definitions of women’s interests, female legislators are more positively related to feminist women’s interests than traditional women’s interests. The result mildly supports the positive moderating effect of quota women on the link between women’s descriptive representation and substantive representation. These findings indicate that women legislators and quota women improve women’s substantive representation in the Republic of Korea. Specific effects of female legislators and quota women on women’s substantive representation are varied depending on different aspects of substantive representation and different definitions of women’s interests.