This paper deals with 3 houses which were planned by Adolf Loos from his middle to late period. The purpose of this paper is to show a process of forming the Raumplan known as Loos's architectural manner, analyzing the inside of each house, especially paying attention to a fragmentary character of elements and the relation between them. To be brief, in villa Mulller, the fragmentization of elements seen in villa Strasser appears again, the integration *of elements with a vertical axis seen in villa Rufer further develops, and the mediation element has for the first time been inserted between fragments.