This secondary battery includes a tubular battery body and a cover member containing the battery body. The cover member includes a tubular body at least covering a side surface of the battery body and a bottom which at least part of a bottom surface of the battery body contacts. The bottom includes an expansion expanded in a direction away from the bottom surface of the battery body, and an end surface of the expansion contacts the insulating plate. The area of the end surface of the expansion is smaller than the area of the bottom surface of the battery body.