A plurality of capacitor cells (10) are layered to form a cell group. On the top of each capacitor cell (10), a pair of electrode plates (10b) is formed to protrude upward. The adjacent electrode plates (10b) are connected to each other. A connection piece (20) protruding upward is attached to each of the electrode plates (10b). The connection piece (20) is connected to a circuit substrate (30). Thus, it is possible to effectively make a connection between the cell group of the capacitor cells (10) and the circuit substrate (30).