Abstract: Provided is a multilayered transmission line plate including a pair of ground layers, a differential wiring disposed between a one-sided ground layer of the pair of ground layers and the other ground layer, an insulating layer (X) disposed between the differential wiring and the one-sided ground layer, and an insulating layer (Y) disposed between the differential wiring and the other ground layer, wherein the insulating layer (X) has a layer containing a resin and not containing a glass cloth; the insulating layer (X) or the insulating layer (Y) has a layer containing a glass cloth and a resin; and the thickness of the insulating layer (X) is equal to or less than the thickness of the insulating layer (Y).