A crimped portion of a positive electrode external terminal is crimped on its upper end side to be electrically connected to a positive electrode terminal plate. This crimped portion is welded to the positive electrode terminal plate by applying high energy beams. The negative electrode side has a configuration similar to that of the positive electrode side. The contact area between the positive electrode terminal plate and the crimped portion of the positive electrode external terminal is set smaller than the corresponding contact area on the negative electrode side, and the volume of the crimped portion of the positive electrode external terminal is set larger than that of the corresponding crimped portion on the negative electrode side. Thus, a prismatic secondary battery is provided that shows strong joining strength between the external terminal and the terminal plate, suppressed internal resistance variations, and improved reliability.