Name and change of style of Chopni were inspected to understand transformation of Chosun costume. During Chosun era Chopni had two significant roles(general) daily clothes and Yungbok; prior to the mid-Chosun it was largely used as daily clothes but after the mid-Chosun it was mainly used as Yungbok, In the case of daily clothes Chopni was utilized as under-coat among various coats and had the name of Chopni symbolizing function of clothes. In the case of YUNGBOK it was used as outer clothing of military men had the name of Cholik symbolizing form of clothes. These facts represent that emphasis was placed on beauty in the case of YUNGBOK to confer ceremonial meaning as outer clothes. In transformation of costume examining by change of Chopni we can see that name and style are changed with role of clothes That is when clothes is used as under such as under-coat name and style mainly represent function whereas they mainly represent beauty when used as outer clothes such as YUNGBOK In addition change of role might be considered as an independent variable which changed name and style dependently. That is change of style produced change of name and time lay between change of style and change of name was found to be about 1 centry.