A substrate includes: a signal line via, a ground line via, and a power supply line via; a first group of first conductor layers formed at a first wiring layer level and coupled to the signal line via, the ground line via, and the power supply line via; a second conductor layer formed at a second wiring layer level and coupled to the power supply line via; a second group of third conductor layers formed at a third wiring layer level and coupled to the signal line via, the ground line via, and the power supply line via; a first insulating layer; and a second insulating layer, wherein the second insulating layer has an opening with a third insulating layer, a relative dielectric constant of the second insulating layer is higher than the first insulating layer and the third insulating layer, and the opening reaches a conductor pattern.