A printed wiring board includes a first insulating layer having concave portions on first surface of the first insulating layer, a first conductor layer including first circuits formed in the concave portions, a second conductor layer including second circuits on second surface of the first insulating layer, a first via conductor connecting the first and second conductor layers, and a second insulating layer formed on the second surface of the first insulating layer and covering the second conductor layer. Each first circuit has upper, lower and side surfaces such that the upper surface is exposed from the first insulating layer and the side and lower surfaces are not roughened surfaces, each second circuit has top, back and side surfaces such that the side and back surfaces are roughened surfaces, and a thinnest first circuit has a line width L1 smaller than a line width L2 of a thinnest second circuit.