This paper summarized the forming, structure and management of the Ui-Jeon(衣廛) in Joseon Dynasty, considered the change of the commercial power of the Ui-Jeon in the $18{sim}19th$ centuries. The Ui-Jeon was established the early period of the Joseon Dynasty. The Ui-Jeon merchants organized the association named Dojung(都中) and were in business with facilities like Haenrang(行廊) and Doga(都家). The Ui-Jeon was mid-sized Si-Jeon, the licensed shop(市廛). The Ui-Jeon held the monopoly of clothes. The Ui-Jeon merchants sold and bought old clothes, sold new clothes, lent the wedding dress for a bridegroom. The Ui-Jeon paid taxes and supplied clothes, goods and sewing labor for the marriage, funeral ceremonies of the royal family. The commercial power of the Ui-Jeon was threatened by free merchants(私商) named old clothes mercants(破衣商). Finally the Ui-Jeon merchants lost the exclusive right to clothes in 1791. After that, the Ui-Jeon merchanrs appealed to the government to give them the monopoly. The Ui-Jeon merchants regained the sole right to sell Ju-ui(紬衣), one item only, but it was temporary. Separately The Ui-Jeon merchants acquired the rights to collect the sub-taxes(分稅) from free merchants.