A printed wiring board includes a core substrate, a first build-up layer, and a second build-up layer. Each build-up layer includes a first insulating layer including reinforcing material, a second resin insulating layer not containing reinforcing material, a first via conductor through the first insulating layer, and a second via conductor through the second insulating layer such that the top diameter of the first via conductor is substantially equal to the top diameter of the second via conductor and that the bottom diameter of the first via conductor is smaller than the bottom diameter of the second via conductor. The conductor layer on the first insulating layer includes a metal foil, a seed layer and an electrolytic plating film. The conductor layer on the second insulating-layer includes a seed layer and an electrolytic plating film and has thickness substantially equal to thickness of the conductor layer on the first insulating-layer.