A wiring board includes electronic components, a multilayer core substrate including insulating layers and conductive layers such that the insulating layers include a central insulating layer in the center position of the core in the thickness direction, a first build-up layer including an insulating layer and a conductive layer such that the insulating layer has resin composition different from that of the insulating layers in the core, and a second build-up layer including an insulating layer and a conductive layer such that the insulating layer has resin composition different from that of the insulating layers in the core. The core has cavities accommodating the electronic components, respectively, and including a first cavity and a second cavity such that the first and second cavities have different lengths in the thickness direction and are penetrating through the central layer at centers of the first and second cavities in the thickness direction.