A wiring board includes an insulator layer having a top surface, and a plurality of pads arranged in a pad arrangement region on the top surface of the insulator layer. The pad arrangement region includes a first region in which a first plurality of pads among the plurality of pads are arranged at a first density, and a second region in which a second plurality of pads among the plurality of pads are arranged at a second density lower than the first density. At least one dummy pad is arranged juxtaposed to at least one of the second plurality of pads in the second region of the pad arrangement region.