A multi-layer substrate includes: a first insulating layer; a conductor layer that is provided on an upper surface of the first insulating layer and that has a penetrating portion; a second insulating layer that covers the conductor layer and that is stacked on the upper surface of the first insulating layer; a via hole that penetrates the second insulating layer from an upper surface of the second insulating layer to reach an inside of the first insulating layer and that includes the penetrating portion; and an insulating member with which the via hole is filled. The conductor layer has a portion exposed in the via hole, and the insulating member covers an upper surface and a lower surface of the conductor layer exposed in the via hole through the penetrating portion of the conductor layer.