To appropriately set a multiple speed by counting track crossing pulses at the time of minimum and maximum multiple speeds of a disk and varying a disk reproducing multiple speed in accordance with the amount of disk vibration discriminated by the difference of the counts.

A signal comparison section 250 compares tracking crossing signals from an error amplifying section 240 with reference signals to generate pulse shaped signals. A microcomputer 260 counts pulse signals from the section 250 at the time of minimum and maximum multiple speeds of a disk, discriminates the amount of vibration by the difference and changes the rotational speed of a spindle motor 270 by the amount of vibration. In other words, the microcomputer 260 subtracts a low multiple speed track crossing count value from a high multiple speed track crossing count value to discriminate a shaft eccentricity disk and a shaft centroid disk, detects the amount of vibration by dividing the subtracted count value by the spindle rotational speed and changes the disk rotational speed by comparing the detected amount with a reference value.