A wiring substrate includes a substrate body including first and second surfaces on opposite sides and a substrate side surface; a penetration electrode penetrating through the substrate body; a first wiring pattern on the first surface and including a first pad; a second wiring pattern on the second surface and including a second pad; a first insulating resin layer covering the first wiring pattern except for an area corresponding to the first pad and having a first resin side surface; a second insulating resin layer covering the second wiring pattern except for an area corresponding to the second pad and having a second resin side surface that is flush with the first resin side surface; a notch part encompassing at least apart of the substrate body and having a resin material provided therein. The substrate side surface is located more inward than the first and second resin side surfaces.