High density mounting and power source sharing are achieved by a digital semiconductor element and an analog semiconductor element provided in a common semiconductor device. A power layer for analog operation is connected to one end of an EBG (Electromagnetic Band Gap) layer, a power layer for digital operation is connected to the other end of the EBG layer, ground terminals for the respective elements are connected to a common ground layer, and a ground layer for separating the power layer for analog operation and the EBG layer from each other is disposed between the power layer for analog operation and the EBG layer. Thereby, high density mounting is achieved along with reducing interference of the power source to an analog chip.