PURPOSE: To detect abnormality in an opening/closing body speedily to stop driving a motor at an early stage by setting a normal operation range having a specified width above and below a specified reference value, and stopping driving the motor when the rotation cycle of the motor deviates from the normal operation range.

CONSTITUTION: When a motor 3 is rotated, a pulse showing that the motor 3 is rotated is outputted from a hall IC 4, and it is inputted to an input terminal 15 of a main control circuit l. The circuit 1 controls abnormal operation detection according to pulses from the hall IC 4, and when the rotation cycle of the motor 3 deviates from a normal operation range, it is judged that abnormality has occured in a device so that the motor 3 is stopped in its driving. It is thus possible to stop driving the motor at an early stage through a speedy detection of abnormality.