An apparatus for controlling a seatbelt system in which the distal end portion of a webbing is moved in the longitudinal direction of a vehicle by a motor, thereby allowing the webbing to be automatically fastened to and unfastened from the body of an occupant. The apparatus has a motor overload detecting circuit which detects an overloaded state of the motor by detecting a change in the current flowing through the motor. When the motor is overloaded, the motor is turned OFF. Accordingly, even when the occupant moves during the movement of the webbing and the webbing consequently interferes with the occupant's neck or head, it is possible to prevent the occupant from feeling uncomfortable and the motor from being burned out.