A secondary battery includes: a wound electrode body in a flat form impregnated with an electrolytic solution; an outer case in a flat form including a lid and a main body, the outer case including a curved portion, the curved portion formed into a curved surface into which the bottom surface and a wall surface of the outer case are connected; and an electric insulating film including a gap through which the electrolytic solution passes, the gap formed at a corner at the bottom surface side of the electric insulating film, the corner with the gap in the electric insulating film being clamped between the curved portion of the inner surface of the outer case and a corner at the bottom surface side of the wound electrode body.