A printed wiring board includes a first buildup layer including first and second interlayer insulating layers, and a second buildup layer formed on the first buildup layer and including the outermost interlayer insulating layer and the outermost conductive layer formed on the outermost interlayer resin insulating layer. The buildup layer includes a first signal line interposed between the first and second interlayer insulating layers, a first ground layer formed on a surface of the first interlayer resin insulating layer, and a second ground layer formed on a surface of the second interlayer resin insulating layer such that the first signal line is interposed between the first and second ground layers, the first and second interlayer insulating layers and the outermost interlayer insulating layer include resin materials, respectively, and the first and second interlayer insulating layers are different from the outermost interlayer insulating layer in material and/or thickness.