The purpose of this study was to analyze the gender role changes of Korean women reflected on their costumes during 20th century. To analyze the diachronic gender role changes, social environments(education, job, economy, family systems, mass-media) of 20 th century were inquired by 10 years and comparatively analyzed with 680 images of representative costumes each periods. The results are as followed. 1) 1900s～1910s: The most representative women's gender role was a wise mother and good wife. Therefore the adopted western costume, a symbol of civilization, were represented women as a passive and sexual object of man. 2) 1920s～1930s: 'Shin Yeosung (Modern Girl)' was the representative gender role of that time. They were the symbol of enlightenment and new education. Their costumes influenced to the changes of traditional Hanbok in functional side. 3) 1940s～1950s: In World War II. a strong and stubborn women were wanted to support their family. They threw feminity and changed their costumes into an active and functional 'Mombbe'. 4) 1960s～19970s: Women asserted Gender equality and resisted the traditional women's gender role. Mini Skirts and Unisex costumes were symbolic costumes reflecting the changes. 5) 1980s: The self confidence of women's gender role affected the androgynous look and bodyconscious look in modern fashion. 6) 1990s～2000s: Now, the dichotomy of gender role is not no longer effective way to understand the social changes and fashion trend rather than personal characteristics and lifestyle trends.