A printed wiring board includes an insulative substrate having a penetrating hole, a first conductive layer formed on a first surface of the insulative substrate, a second conductive layer formed on a second surface of the insulative substrate, and a through-hole conductor formed in the penetrating hole through the insulative substrate such that the through-hole conductor is connecting the first conductive layer and second conductive layer. The penetrating hole has a first opening portion formed on a first-surface side of the insulative substrate and a second opening portion formed on a second-surface side of the insulative substrate such that the second opening portion has a depth which is greater than a depth of the first opening portion and the second opening portion has a volume which is greater than a volume of the first opening portion, and the through-hole conductor formed in the second opening portion includes a void portion.