A printed wiring board includes an insulating substrate having openings, a first conductor layer formed on a first surface of the insulating substrate, a second conductor layer formed on a second surface of the insulating substrate, magnetic material portions formed in the openings of the insulating substrate and having through holes extending from the first surface to second surface of the insulating substrate, and through-hole conductors formed on side walls of the through holes such that the through-hole conductors connect the first conductor layer and second conductor layer. The magnetic material portions include magnetic particles and resin such that the magnetic particles include particles forming the side walls and that gaps are formed between the particles and the resin, and each of the through-hole conductors includes a chemical copper plating film such that the chemical copper plating film is deposited in the gaps formed between the particles and the resin.