PURPOSE: To obtain the sufficient accuracy of positioning by connecting a waveform generating circuit to a bang-bang control circuit and controlling the speed of a motor with time by the voltage of the waveform generating circuit.

CONSTITUTION: When a waveform generating circuit 1 is started by an external starting input 5, voltage is applied to a motor driver 2 from the waveform generator 1, and a DC motor 7 is turned. Voltage corresponding to movement is outputted from a position sensing section 4 sensing a position corresponding to the revolution of the DC motor 7 at that time. The voltage is fed to a polarity electronic switch 3 changing over the direction of rotation of the motor driver 2, and the stoppage of the forward and reverse rotation of the DC motor 7 is controlled. When a waveform lowering with time is generated from the waveform generating circuit 1, the DC motor 7 can be stopped smoothly.