Many experiences about“corrugation of bottom shell plating”were reported recently. This is the phenomenon to be seen when the stress on the surface of plate after buckling exceeds the yielding point, and is called the permanent buckling. In this paper, the author dealt with the plate problem after buckling of bottom shell plating according to the large deflection theory, and estimated the limiting stress of this failure in such cases of flat mild steel plate, high tensile steel plate, suffering water pressure, and having the initial deflection. After several considerations, the author concluded, as the effectiveness of panel breaker and the influence of the initial deflection, essential difference existed between large and small ships.