A wiring substrate includes a core substrate, and a build-up part formed on the core substrate and including insulating layers and conductor layers. The conductor layers include one or more conductor layers each having a first wiring and a second wiring such that the second wiring has a conductor thickness smaller than a conductor thickness of the first wiring and that a minimum value of a line width of a wiring pattern of the second wiring is smaller than a minimum value of a line width of a wiring pattern of the first wiring.