A method of forming a magnetic head comprises the steps of: selectively exposing through the use of a photomask a photoresist layer unpatterned; forming a pattern for forming a pole layer by developing the photoresist layer after the exposure; and forming the pole layer through the use of the pattern. The photomask includes first to third regions. The first region has such a perimeter that a projection image thereof is shaped along a perimeter of an ideal shape of the top surface of the pole layer. The second region touches the perimeter of the first region, and is located outside the first region. The third region is located inside the first region without touching the perimeter of the first region. The third region suppresses deviation of the pole layer from its desired shape which may be caused by the effect of light reflected while the photoresist layer is exposed.