An electric double-layer capacitor is provided in which an upper end portion of a recessed container is sealed by a sealing plate. An electrode and an electrode are accommodated in a hollow portion formed by a recessed portion and the sealing plate. One step portion is formed in the middle of one inner peripheral surface of the recessed portion, and another step portion is formed in the middle of the other opposing inner peripheral surface. The one step portion and said another step portion are formed at the same height, and upper surfaces of those step portions exist on the same plane.