A wiring substrate comprises an insulating substrate and an external electrode on the insulating substrate. The insulating substrate comprises a lateral surface comprising a cutout. The cutout extends to a lower surface of the insulating substrate. The external electrode extends from an inner surface of the cutout to the lower surface of the insulating substrate. The insulating substrate comprises a protrusion at a lower end portion of the inner surface of the cutout. The protrusion protrudes from the inner surface of the cutout toward the lateral surface of the insulating substrate.