When an operation switch of a motor control circuit is switched on or when the operation switch and an automatic operation switch are simultaneously switched on, a switching device is switched on to energize a relay winding and a contact in the relay is switched to drive a motor. When an overcurrent is passed to a current detecting resistor and a temperature rise in the current detecting resistor is detected by the temperature dependent resistor and/or when a rise in a voltage across terminals of the current detecting resistor is detected by an overvoltage detecting circuit, the switching device is switched off via the bias circuit to thereby stop the driving of the motor.