As a result of the Ako-incident in 1701, the Ako Castle was confiscated. Based on the manuscripts, this paper clarifies the relation between the social position (Karokudaka) and the rooms' arrangement of Samurai (Daimyo Kachu) House. As the result of analysing, the physical area of the classified rooms (Genkanbu, Omote, Oku, Daidokorobu) is in proportions to the social position (Karokudaka), while their ratios in the main building are almost invariable. This is considered to derive from the role of the social position of Samurai (Daimyo Kachu).
