A wiring substrate includes an insulating base that has a plate surface; a first circuit that is provided on the plate surface; a first terminal that is provided on the plate surface, and to which a mounting member is attached; a second terminal that is provided on the plate surface; a first wiring that connects the first circuit and the first terminal to each other; and a second wiring that connects the first terminal and the second terminal to each other, is electrically connected to the first wiring in the first terminal, and has a parallel section in which the second wiring is disposed close to and parallel to the first wiring without being electrically connected to the first wiring outside the first terminal.