A wiring board includes core substrate, a first build-up layer on first surface of the substrate and including conductive and insulating resin layers, and a second build-up layer on second surface of the substrate and including conductive and insulating resin layers. The first build-up is formed such that each conductive layer includes a metal foil layer and a plating layer on the foil layer and the foil layer of a conductive layer on an outermost resin layer has thickness greater than thickness of the foil layer of a conductive layer on a non-outermost resin layer, and the second build-up is formed such that each conductive layer includes a metal foil layer and a plating layer on the foil layer and the foil layer of a conductive layer on an outermost resin layer has thickness greater than thickness of the foil layer of a conductive layer on a non-outermost resin layer.