A disk-shaped magnetic recording medium having a reference track and a
plurality of data tracks is rotated by a motor which generates an index
signal at a predetermined position. A magnetic head is slightly moved in
the radial direction of the medium for each predetermined unit distance
smaller than the data track width, and a reproduction output amplitude
measuring circuit measures the reproduction output amplitude of a signal
read from the data track for each index signal. A CPU obtains a position
where the amplitude has the maximum value based on the number of head
movements and the amplitude at that time so as to control data track
positioning. Further, the CPU calculates a relative position between the
data track position and the reference track position to perform reference
track positioning. The data or reference track positioning of the magnetic
head can be performed accurately in a short time.
