Standardization of concrete caisson for breakwater was carried out in this paper.
　If standardization were made on a whole caisson, it would be necessary to consider numerous types of caisson. Therefore, Caisson were divided into slabs, walls and separating walls, and standardization was made on these devided members. As a result, though unimportant problems are left unsolved in the reinforcement at the connection of members, the standardization could be achieved satisfactorily.
　The dimension of caisson is as follows;
　slab, length and width ; 3.0, 3.5, 4.0, 4.5, 5.0(m)
　　load acting on the slab ; 5, 10t
　　load acting below the slab ; 10, 20, 30,40(t)
　wall and separating wall ;
　　height ; 4, 5, 6, 7, 8, 9, 10, 11, 12, 14(m)
　　width ; 3.0, 3.5, 4.0, 4.5, 5.0(m)
　The calculations of bending moment were carried out by using charts made in 1968 by Messrs. Horii and Moto, assumming that slab had four fixed edges and each of wall and separating wall had one freed edge and three fixed edges.