To prevent generation of malfunction due to the stopping of phase energization switching, by involving a phase energization switching monitoring means which monitors the presence or absence of phase energization switching in a stepping motor while it is driven, and a stopping control means for stopping a stepping motor if a monitoring means detects the continued condition without switching phase energization for a prescribed time.

A phase energization switching means for monitoring the presence or absence of phase energization switching in a stepping motor 1 while it is driven involves a differentiating circuit 4 serving as a pulse detecting means for detecting the trailing edge of a pulse controlling energization switching, and a timer circuit 5 serving as a timer means for restarting clocking after a reset operation, are provided. As a stopping control means for stopping the stepping motor 1 if a prescribed time has passed without energization switching, an AND gate 6 is formed which serves as an energization release means for waiting for the elapse of prescribed time in a clocking by the timer circuit 5 and stopping a motor control signal K. It is thus possible to prevent the stepping motor and the motor drive circuit from being broken.