A printed wiring board includes a resin insulating layer, a wiring conductor layer embedded in the insulating layer such that the wiring layer has first surface exposed from the insulating layer, and a conductor post formed in the insulating layer and on second surface of the wiring layer on the opposite side with respect to the first surface of the wiring layer such that the conductor post has side surface covered by the insulating layer and end surface exposed from the insulating layer on the opposite side with respect to the wiring layer. The conductor post is formed such that the side surface of the conductor post is a roughened side surface having surface roughness of first roughness R1, the end surface of the conductor post is a roughened end surface having surface roughness of second roughness R2, and the first and second roughnesses R1, R2 satisfy R1>R2.