Manufacturing method for a printed wiring board

A method includes the steps of forming a first metal foil (82) on a surface of an insulator substrate (1a), drilling, with a thermosetting resin film (84) temporarily fixed to an opposite surface of the substrate, a through hole (86) simultaneously in the first foil, the substrate, and the resin film, simultaneously heating and vacuum-pressing the first foil, the substrate, the resin film, and a second metal foil (87) brought into contact with the resin film to obtain an intermediate board in which a bottom of the through hole is covered with the second foil and has a corner with a corner rounded portion (93) formed by the resin film, and forming a metal plating layer (95) on the first and the second foils, on the bottom and an inner wall of the through hole, and on the corner rounded portion to obtain a final printed wiring board.