To enable the uniformity of thickness and the formation of a fitting space without going through another process in a method for manufacturing a battery case having the fitting space for fitting a cover to an upper edge inner circumference by impact press.

A press process and a finishing process are included. In the press process, slag 14 is filled into a cavity 13 of a die 12, and a punch 15 is made to fall into the cavity 13 to impulsively press the slag for plastic deformation, manufacturing a case original mold 5. In the finishing process, by using a punch 24 comprising a die 22 having a dice hole 23 with an inner diameter equal to a battery case outer diameter, an insertion part 25 with an outer diameter equal to a battery case inner diameter, and a large diameter part 26 provided connectedly to an upper edge of the insertion part 25 and having an outer diameter equal to an inner diameter of a fitting space 4 of the battery case, the case original mold is caused to pass through the die hole with the insertion part inserted into the case original mold to make the thickness of a side wall of the case original mold uniform and also form a fitting space for fitting a cover.