A wiring substrate in which a plating layer is sufficiently plated on a surface metal layer and which has an excellent reliability is provided. A wiring substrate includes an insulating base; a heat dissipation member disposed in the insulating base, the heat dissipation member partially exposed from the insulating base, the heat dissipation member containing Cu; a surface metal layer disposed on a surface of the insulating base, the surface metal layer contacting and covering the heat dissipation member, the surface metal layer containing Mo as a main component, the surface metal layer including a surface portion containing Cu; and a plating layer disposed on the surface metal layer, wherein Cu contained in the heat dissipation member and Cu contained in the surface portion are bonded to each other.