A printed wiring board includes a conductor layer, an outermost resin insulating layer having a first surface and a second surface on the opposite side with respect to the first surface and laminated on the conductor layer such that the second surface faces the conductor layer, and metal posts formed in the outermost resin insulating layer such that the metal posts are penetrating through the outermost resin insulating layer and reaching the conductor layer. The metal posts include first metal posts and second metal posts such that each of the first metal posts has a first upper surface positioned above the first surface of the outermost resin insulating layer and having an entirely flat surface and that each of the second metal posts has a second upper surface positioned above the first surface of the outermost resin insulating layer and having a partly flat surface.