PURPOSE: To improve joining strength and combined efficiency of a can by combining top sheet or bottom sheet to the can body as double seaming irradiating laser beam around center of the seaming part and joining as melting over the whole circumference in plural pieces of the metal plates.

CONSTITUTION: A body hook 4 is formed to the can body 1 with bending work and cover hook 5 for joining are formed to the top sheet 2 or bottom sheet 3 side. Successively, after forming the seaming part 6 by overlapping the hooks 4, 5, the center part of the can seaming part 6 is laser-welded over the whole circumference with a laser beam irradiating apparatus set at outside. To plural pieces of the metal sheets 1W5, suitable pieces of integrated melting weld can be executed. By this method, as the metal sheets 1W5 can be mutually welded as integrating, the can body 1 and the top sheet 2 or bottom sheet 3 are firmly joined and the joined strength is improved. As the working speed is rapid, the combined efficiency of the can is improved.