To prevent replacement display from being generated even when a loaded battery voltage value V drops to a first threshold level YV1 during forcible out-of-step control; and, if the loaded battery voltage value V drops to a second threshold level YV2 which is set lower than the first threshold level YV1 during forcible out-of-step control, to disable operation of a stepping motor thereafter.

A battery voltage monitoring method is adopted in an apparatus which, comprising a motor-operated item including a movable body driven by a stepping motor, an electronic control unit, and a dry battery as a power supply for the stepping motor and the electronic control unit, exerts forcible out-of-step control to output drive pulses for the stepping motor while the movable body is hindered from moving by a stopper provided in the motor-operated item. Further, the battery voltage monitoring method is so devised that when a loaded battery voltage value drops to a first predetermined threshold level and a replacement display is generated prompting for replacement of the dry battery, the user may not be displeased by a replacement display which will otherwise be unnecessarily generated during forcible out-of-step control.