This method for clinching a can cover has a small diameter center panel formed from a center panel, ring-shaped reinforcing groove, chuck wall, and curled part in which the ratio of the center panel diameter and can cover diameter is 0.65-0.75. The chuck wall is provided with a first inclined part and a second inclined part that are inclined toward the outside. When a flange tip part of a can body and the curled part of the can cover are superimposed in a virtual horizontal plane, a lower end part of the second inclined part or a second curved part that connects the first inclined part and second inclined part is positioned in a position in a range of an angle of 0°-35° to a virtual horizontal plane passing through the center of the curve of a rounded part of the flange.