A wiring substrate includes first and second wiring structures. The first wiring structure includes a core substrate, first and second insulation layers formed from a thermosetting insulative resin respectively including first and second reinforcement materials, and a via wire formed in the first insulation layer. The second wiring structure includes a third insulation layer formed on an upper surface of the first insulation layer and an upper end surface of the via wire, and a wiring layer extended through the third insulation layer and electrically connected to the via wire. The outermost insulation layer, the main component of which is a photosensitive resin, is stacked on a lower surface of the second insulation layer. The second wiring structure has a higher wiring density than the first wiring structure. The first reinforcement material is partially exposed on the upper surface of the first insulation layer.