To provide a highly reliable printed wiring board that has a conductor layer as a core in its inside and is high in mounting density and superior in radiation or mass-production, and to provide its manufacturing method.

The printed wiring board includes two or more metal foils and at least one or more core conductor layers 111, and the metal foil is arranged at least by one layer on both sides of the core conductor layer. An insulation layer is interposed between the metal foil and the core conductor layer, and a via hole of a through hole and/or an inner via hole is provided to electrically connect the metal foils without electrically connecting them with the core conductor layer. The core conductor layer is 0.3-0.4 mm in thickness, and the diameter d of a prepare hole for forming a via hole of the core conductor layer is 1.0-3.0 mm. The distance L of an area between the adjoining prepared holes therefor in the radial direction of the hole is 80% of the diameter d of the prepared hole therefor.