The system includes a magnetic head which faces a recording medium. The magnetic head has a coil which generates magnetic fields. The magnetic head also has a pole layer which is formed using a pattern. The pole layer allows magnetic flux generated by the coil to write data onto the recording medium. The pole layer generates a write magnetic field for writing data onto the recording medium.A photomask is used to form the magnetic head. The photomask includes three 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, and the second region touches the first region's perimeter. 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.