A printed wiring board includes an insulator having a first surface, and a second surface opposite to the first surface, a through-hole penetrating from the first surface to the second surface, and a metal plated layer formed on the first and second surfaces of the insulator, and on an inner peripheral surface of the through-hole, wherein an inside diameter of the through-hole gradually decreases from the first surface toward the second surface of the insulator. An average diameter of the through-hole is 20 μm or greater and 35 μm or less at the first surface, and is 3 μm or greater and 15 μm or less at the second surface, and an average thickness of the metal plated layer formed on the first and second surfaces is 8 μm or greater and 12 μm or less.