A wiring board comprising a first surface on which a first electrode is disposed and a second surface on which a second electrode is disposed; at least a single insulation layer and at least a single wiring layer; and one or a plurality of mounted semiconductor elements, wherein the second electrode disposed on the second surface is embedded in the insulation layer, the surface on the opposite side of the exposed surface on the second surface side of the second electrode is connected to the wiring layer, and all or part of the side surface of the second electrode does not make contact with the insulation layer.