A printed wiring board includes a resin insulating layer, pads formed on the resin insulating layer, an uppermost resin insulating layer formed on the resin insulating layer such that the uppermost resin insulating layer is covering the pads and has openings exposing the pads, respectively, via conductors formed in the uppermost resin insulating layer such that the via conductors are formed on the pads exposed from the openings in the uppermost resin insulating layer, respectively, and metal posts formed on the via conductors such that each of the metal posts has a portion on a surface of the uppermost resin insulating layer around the via conductors and a side surface having a flared bottom extending toward the uppermost resin insulating layer.