METHOD OF MANUFACTURING ELECTRICITY STORAGE DEVICE

A method of manufacturing an electricity storage device includes a first preparing step of preparing a case body including an open end, a second preparing step of preparing a sealing plate for sealing the open end of the case body, an assembling step of attaching the sealing plate to the open end of the case body, and a welding step of welding the case body and the sealing plate by applying a laser beam along a boundary between the case body and the sealing plate. The sealing plate prepared in the second preparing step includes a recessed portion recessed downwardly in a circumferential end portion of an upper surface of the sealing plate. In the welding step, a laser beam is applied to the recessed portion of the sealing plate to weld the case body and the sealing plate.