A wiring board having an insulation layer, and a buildup structure formed on the insulation layer and including insulation layers. The insulation layer and the buildup structure form a board structure in which a cavity portion having an opening on a surface of the buildup structure on the opposite side of the insulation layer is formed. The cavity portion is extending through one or more of the insulation layers in the buildup structure and has a groove portion formed on the bottom surface of the cavity portion along a wall surface of the cavity portion. The board structure composed of the insulation layer and the buildup structure has a pad formed on the bottom surface of the cavity portion in a position farther from the wall surface of the cavity portion than the groove portion.