A printed wiring board includes a first build-up layer having first insulating layer, conductor layer and via conductor, a second build-up layer formed on the first build-up layer and having second insulating layer, conductor layer and via conductor, a third build-up layer formed on the second build-up layer and having third insulating layer, conductor layer and via conductor, and a fourth build-up layer formed on the third build-up layer and having fourth insulating layer, conductor layer and via conductor. The first insulating layer has a thickness that is larger than a thickness of the second insulating layer, the thickness of the second insulating layer is larger than a thickness of the third insulating layer, the thickness of the second insulating layer is larger than a thickness of the fourth insulating layer, and the thickness of the fourth insulating layer is larger than the thickness of the third insulating layer.