A wiring substrate includes a resin insulating layer, a conductor pad formed on the resin insulating layer, a coating insulating layer formed on the resin insulating layer such that the coating insulating layer is covering the conductor pad, and a metal post connected to the conductor pad and protruding from the coating insulating layer such that a gap is formed between the metal post and the conductor pad at a peripheral edge of the metal post. The coating insulating layer is formed such that the coating insulating layer has an interposed portion formed in the gap between the metal post and the conductor pad at the peripheral edge of the metal post.