A wiring board includes a core substrate having a structure including an insulating base material and a large number of filamentous conductors densely provided in the insulating base material and piercing the insulating base material in a thickness direction thereof. Pads made of portions of wiring layers are oppositely disposed on both surfaces of the core substrate and electrically connected to opposite ends of a plurality of filamentous conductors in such a manner that the pads share the filamentous conductors. A wiring connection between one surface side and the other surface side of the core substrate is made through the pads. The insulating base material is made of an inorganic dielectric. Pads made of portions of the wiring layers are disposed on both surfaces of the core substrate and electrically connected only to corresponding one end sides of different groups each formed of a plurality of filamentous conductors.