To prevent malfunctions in a circuit for controlling the start/stop of a motor by surely initializing its predetermined circuit, when starting the motor.

A sensing circuit 3 measures and senses via a sensor S the internal temperature of a motor M, to output a stop signal of the motor M, when the measured temperature value exceeds a reference value. A retaining circuit 5 retains the output of the stop signal of the motor M, until the feeding of a power supply to the retaining circuit 5 is turned off. A control-signal output circuit 7 outputs a rotation controlling signal for controlling the rotation of the motor M and interrupts the output of the rotation control signal by the stop signal of the motor M. When the feeding of the power supply to the retaining circuit 5 is turned on, an initializing circuit 13 outputs an initializing signal which rises with a time constant longer than the time constant of the retention circuit 5 for operating it therewith stably, to initialize the retention circuit 5.