The main magnetic pole piece of a magnetic head for perpendicular magnetic recording preferably has an inverted trapezoidal shape in order to maintain a sufficient recording magnetic field. Embodiments of the present invention enhance the covering power of the protective film around the main magnetic pole piece of the magnetic head and thereby ensure reliability even when the main magnetic pole piece has such a shape. In one embodiment, the protective film for protecting the main magnetic pole piece is formed by a sputtering apparatus while applying a bias, or it is formed by a carousel type sputtering apparatus or the chemical vapor deposition (CVD) technique.