Magnetic disk apparatus, method for determining data track pitch, and self-servo write method

A self-servo reference signal including a timing pattern and an oblique phase pattern is transferred in advance on a magnetic disk 1 by magnetic printing. A phase difference detection section 13 detects a phase difference between the two patterns to detect the position of a magnetic head 2. A burst signal generated by a record signal generation section 14 is recorded in a region of the magnetic disk 1 where no self-servo reference signal is recorded. A track pitch calculation section 11 determines a relationship between the reproduction output of the burst signal detected by a reproduction signal processing section 12 and the phase difference detected by the phase difference detection section 13, thus calculating an optimum data track pitch.