A wiring substrate comprises a conductor pattern embedded in an insulating layer, the insulating layer having an opening to expose top and bottom faces of the conductor pattern and define a terminal of the wiring substrate, a torsion restrictor formed in the conductor pattern at a location passing over an edge of the opening, the torsion restrictor restricting torsion of the terminal, and an easily extensible part formed on at least one of the torsion restrictor and a portion of the terminal adjoining the torsion restrictor, the easily extensible part allowing the conductor pattern to longitudinally extend toward the opening.