Embodiments of the inventive concept include a semiconductor device having a circuit board including a first outer layer, a contact region in the first outer layer, a second layer formed on an opposite side of the first outer layer, a via-hole, and a plurality of inner layers formed to be stacked between the first layer and the second layer. A case may accommodate the circuit board. The case may have a projection portion that is configured to come in contact with the circuit board in the contact region. The plurality of inner layers may include a ground layer. The first outer layer may be connected to the ground layer through a via-hole. The case may be connected to the ground layer through the first outer layer.