A manufacturing method for a square battery includes: a first process in which an outer terminal and an outer side resin member that separates the outer terminal and an outer surface of a lid body are assembled to the lid body; a second process in which a laser beam is irradiated from the outer surface side of the lid body to weld the lid body to the case body by laser after the first process; and a third process in which the outer side resin member is expanded after the second process.