A printed wiring board includes a first insulating layer, a conductor layer on the first insulating layer, and a second insulating layer formed on the first insulating layer and covering the conductor layer. The conductor layer includes first, second and third circuits, the first circuit has first width of 15 μm or less, the first and second circuits have second space between the first and second circuits such that the second space has second width of 14 μm or less, the first and third circuits have third space between the first and third circuits such that the third space has third width of 20 μm or more, and the first circuit has first lower and upper surfaces, and second and third side walls such that second angle between the second wall and the first lower surface is larger than third angle between the third wall and the first lower surface.