A wiring substrate includes an insulating layer, a conductor layer formed on a surface of the insulating layer and including a conductor pad, a covering layer formed on the insulating layer and covering a portion of the insulating layer, an optical waveguide positioned on the surface of the insulating layer and including a core part, and a conductor post including plating metal and formed on the conductor pad such that the conductor post is penetrating through the covering layer and connected to a component. The insulating layer has a component region covered by the component when the component is connected to the conductor post, the core part has an end surface facing the opposite direction with respect to the insulating layer and exposed in the component region and a distance between the end surface and the surface of the insulating layer is greater than a thickness of the covering layer.