The purpose of this study is to analyze the major influence of postmodernism on 20th century fashion. Due to its characteristic traits like pluralism, indeterminacy, and immanence, it can be said that postmodernism in fashion manifests itself in an overlapped and duplicated style. The conceptual side has to do with such various 20th century thoughts as decanonization, deconstruction, populism, and in fashion it is presented as subcultural style, syncretic style, and post-feminist style. The stylistic side of postmodernism in fashion also has to do with fragmentation, hybridity, stress on performance and participation, carnivalization, deconstructive turn, and it is presented as hybrid expression, deconstructive technique, performance, and so on. In the latter part of the 20th century in which postmodernism blossoms in various fields, fashion also participates in the current of the times, together with the rapid stylistic turn, the co-existence of various trends, and the experimental or avant-garde new trials. However, it should be said that all of these tendencies mean not so much blurring of the boundaries between styles as developmental mixture of styles coming from juxtaposition after fully realizing the boundaries of contrast and combination.