A wiring substrate includes a heat sink, an insulation layer, first and second wiring layers, first and second through wirings, and first and second pads. The insulation layer is arranged on the heat sink with an adhesive layer located in between. The insulation layer includes first and second through holes. The first and second wiring layers are arranged on a surface of the insulation layer in contact with the adhesive layer. The first and second wiring layers are embedded in the adhesive layer. The first through wiring formed in the first through hole is connected to the first wiring layer and thermally coupled to the semiconductor device. The second through wiring formed in the first through hole is connected to the second wiring layer and electrically connected to the semiconductor device. The pads cover exposed surfaces of the through wirings.