In a head position control device having a disturbance suppression
function and eccentricity correction function, the interference between
the eccentricity correction function and the disturbance suppression
function is prevented. An eccentricity correction function and
disturbance suppression control function are provided in the head
positioning control system, and an interference prevention function,
which detects the disturbance suppression frequency and turns OFF the
feedback of the eccentricity correction control for the eccentricity
correction frequency near the disturbance suppression frequency, or
shifts the disturbance suppression frequency from the eccentricity
correction frequency, is provided. Therefore the interference between the
eccentricity correction and the disturbance suppression can be prevented,
and unstable eccentricity correction can be prevented.