A semiconductor device includes a plurality of core chips and an interface chip that controls the core chips. Each of the core chips and the interface chip includes plural through silicon vias that penetrate a semiconductor substrate and plural pads respectively connected to the through silicon vias. The through silicon vias include a through silicon via of a power source system to which a power source potential or a ground potential is supplied, and a through silicon via of a signal system to which various signals are supplied. Among the pads, at least an size of a pad connected to the through silicon via of the power source system is larger than a size of a pad connected to the through silicon via of the signal system. Therefore, a larger parasitic capacitance can be secured.