This paper is to study the development background of casual Korean clothes through the consideration of the style change of traditional clothes. The purpose of this study is to present the method for the settlement of casual Koran clothes as everyday clothes and to present the direction which casual Koran clothes follow in the future. The development. The development backgrounds of casual Korean clothes are as followings. 1) the self-awakening for the importance of national culture. 2) practical aspects 3) the change of life style accompanied with economic growth 4) the development of mass media Casual Korean clothes in the future should be studied and developed in following aspects. 1) practical aspects by developing design for easy activity 2) environmental aspects by natural dyeing which is harmless to human body and the nature 3) emotional aspects by regarding traditional beauty as importance 4) color sense aspects according to scarcity of as form change of the Korean clothes 5) production aspects by mass production of ready-made clothes not order clothes 6) diplomatic aspects as folk costume which is corresponding with international trend 7) scientific aspects by developing many patterns according to various bodies 8) economic aspects by low price through the mass cultivation of natural materials 9) fashionable aspects by subdividing traditional clothes to ceremonial clothes, everyday clothes, working clothes.