A wiring substrate includes a wiring board having a main face and a side face substantially perpendicular to the main face; a circuit pattern which is formed on the main face of the wiring board; a soaking plate which is disposed in an intermediate layer of the wiring board; and a plurality of protruding terminals are disposed in the intermediate layer and are projected outwardly from the side face. The protruding terminals are electrically connected in the intermediate layer to each other.