A printed wiring board includes a first conductor layer, a resin insulating layer formed on the first conductor layer, a second conductor layer formed on a surface of the resin insulating layer and including a signal wiring, and a via conductor formed in the resin insulating layer such that the via conductor is connecting the first conductor layer and the second conductor layer. The resin insulating layer has an opening such that the opening is exposing a portion of the first conductor layer and that the via conductor is formed in the opening of the resin insulating layer, and the resin insulating layer includes inorganic particles and resin such that the resin is forming the surface of the resin insulating layer.