This study empirically examined Seo Yu-gu`s views on constumes that are based on `Boksikjigu[服飾之具]` of Seomyongji[贍用志] in Imwonkyungjeji[林園經濟志]. In `Boksikjigu`, Seo Yu-gu explained different situations and problems that were related to costumes and proposed solutions for the problems. This study examined the contents, and divide the items into caps, accessories, and clothes. The results of this study were as follows. First, Seo Yu-gu in he rited the tradition of erudition. Seo Yu-gu classified various costume items systematically, and explained in detail about the origin, history and materials of the costume items. Second, he emphasized frugality, effective use, and welfare. Seo Yu-gu argued that the sleeves should be shortened for convenience and tried to improve practicality in the functional aspect. Also, he wanted to enrich people`s life by improving the convenience of goods used in daily life. Third, he tried to establish identity as a Confucian intellect. This idea was clearly shown in `costumes`; therefore, they served as evidences that Seo Yu-gu used to correct wrong practices through precise historical investigation and review of Shim-ui[深衣], the symbol of the practice of Jujagarye[朱子家禮]. In his later years, he discovered the plain dress that was worn as a casual wear by ZhuXi[朱熹]and tried to wear it in dailylife.