A method of producing a printed circuit board includes: forming a metal layer on a support plate; forming a mask layer on the metal layer; forming a pattern plating having a stem as plating up to a level of the mask layer, and a cap as a portion of plating exceeding the mask layer and having an outgrowth lying over the surface of the mask layer; laminating an insulating base on a conductive circuit board constituted by the support plate, the metal layer and the pattern plating to form a circuit board intermediate in which the pattern plating is buried in the base; removing the support plate and the metal layer to form an exposed surface; and mechanically polishing the exposed surface until the stem of the pattern plating is removed, to increase the width of the conductive pattern on the exposed surface.