<p>An accumulator includes: an accumulation element having a first electrode and a second electrode positioned at different sides in a predetermined direction; a first terminal connected to the first electrode; a second terminal connected to the second electrode; and a resin case covering the accumulator element so that the external surface of the first terminal and the external surface of the second terminal will be exposed. The accumulation element has a substantially rectangular shape viewed from its predetermined direction. The resin case substantially has a substantially rectangular shape viewed from its predetermined direction. The resin case has a first face and a second face arranged at the opposite sides in its predetermined direction and a third face connected to the first face and the second face. The first terminal is exposed to the first face of the resin case. The second terminal has a shape along the first face and the third face of the resin case over the accumulation element and is exposed to the first face. This accumulator has a small size, a large capacity, and a high reliability.</p>