The objectives of this study are to consider about the research of a costume and a discussion about a system of costume by practical science scholar in the late period of Chosun Dynasty. The result are descrived as follows: 1. The purpose that practical science scholars researched a costume was not only the intellectual research but also to make a basis in order to reform a uncorrected costume`s system. Their study had two point. The one was the investigating research about the origin and change of the costume. The other was the study about a formation of costume. 2. The practical science scholars determined the directions to reform a wrong costumes` system on the basis of the research about a costume.. They had three directions. Those were a conservatism, a rationalism to think the realities of life and a reformation. 3. The practical science scholars` thinking was to pursue the origin form and the practical use. This two axis show the direction to improve our costume`s culture now a day.