A circuit board has a curved portion provided in at least one side of an external shape thereof. An external connecting terminal is provided on a first main surface of the circuit board. A semiconductor element is mounted on a second main surface of the circuit board. A first wiring network is provided in a region except the terminal region on the first main surface. A second wiring network is provided on the second main surface. Distance from the side including the curved portion to the first wiring network is larger than distance from at least one of the other sides to the first wiring networks, and distance from the side including the curved portion to the second wiring network is larger than distance from at least one of the other sides to the second wiring networks.