A wiring substrate includes a first wiring layer; a first insulation layer including a reinforcement material and a first opening extending through the reinforcement material and exposing a partial region of an upper surface of the first wiring layer, in which an end of the reinforcement material projects in the first opening; a second insulation layer not including a reinforcement material, covering an upper surface of the first insulation layer, a wall surface of the first opening, and a first part of the partial region and an entire surface of the reinforcement material projecting in the first opening, and including a second opening exposing a second part of the partial region; and a second wiring layer including a wiring portion formed on an upper surface of the second insulation layer and a via portion formed in the second opening and connecting the wiring portion to the first wiring layer.