A wiring substrate includes first and second wiring structures. The first wiring structure includes a core substrate, first and second insulation layers each formed from a thermosetting insulative resin including a reinforcement material, and a via wire formed in the first insulation layer. The second wiring structure includes a wiring layer formed on upper surfaces of the first insulation layer and the via wire, an insulation layer formed on the upper surface of the first insulation layer, and an uppermost wiring layer including a pad used to electrically connect a semiconductor chip and the wiring layer. An outermost insulation layer stacked on a lower surface of the second insulation layer exposes a portion of a lowermost wiring layer stacked on the lower surface of the second insulation layer as an external connection pad. The second wiring structure has a higher wiring density than the first wiring structure.