PURPOSE: To attain a circuit without trouble by erroneous operation and is formed easily into an IC constitution by controlling a motor, which rotates and drives a digital audio disc, on a basis of the output of a phase comparing circuit.

CONSTITUTION: A reference frequency signal (RET) is inputted to one input of a phase comparing circuit 7, and a comparison signal having a frequency corresponding to the rotation state of a motor is inputted to the other. The output of the phase comparing circuit 7 is applied to a driver circuit 73 through a low-pass filter 72, and the rotation of a motor 74 is controlled by the output of this driver circuit 73. A shift register 60, gates 61, 63, 64, 65, and 66, and a counter 62 constitute a circuit which generates the comparison signal having a frequency corresponding to the rotation state of the motor. The shift register 60 and the gate 61 are provided for detecting the pattern of a synchronizing signal out of a reproduced digital signal (the output of a flip flop 11). In the compact disc system, the continuously of 11-bit maximum signal inversion intervals is defined as the synchronizing signal.