A wiring substrate includes a substrate body formed of an inorganic material and including a first surface and a second surface, a first trench formed in a first surface side of the substrate body, a second trench formed in a second surface side of the substrate body, a penetration hole penetrating through the substrate body, a first plane layer filling the first trench, a second plane layer filling the second trench, and a penetration wiring filling the penetration hole. The first plane layer is a reference potential layer. The second plane layer is a power supply layer.