I have made a study of the formation and the characteristics of Korean Mask Dance and Play, the expansion and the process of each section, the type of the casts and the pattern of Masks for understanding the frame and the principles of Korean Dance and play. The conculsions are as follows ; ·Korean Mask Dance and Play is originated in the Village Festival and has been changed to playing only Drama and Dance. ·Each section of Korean Mask Dance and Play grows independently without the law of causality. ·The contents of Korean Mask Dance and Play is based on the structure of the fight for the other sex. ·Korean Mask Dance and Play begins at the point of their life circle. ·Korean Mask Dance and Play is free from the condition of time and space. ·The players and spectators give and take mutually during playing the Dance and Dram. ·The casts stand for their own grades. ·In Korean Mask the complex characters of Casts are filled at the same time.