The invention relates to a method for actuating a reversible belt pretensioner for pretensioning a belt webbing, wound around a belt reel, of a seat belt in a motor vehicle, the belt pretensioner having a drive which acts on the belt reel. The seat belt has a locking device, acting on the belt reel in the unwinding direction, as a belt extraction lock. After the triggering of the belt pretensioner and when a predefinable condition is met, the belt pretensioner is actuated in such a way that the belt reel rotates at least to such an extent in the winding-up direction that the locking device of the belt reel opens and releases the belt webbing for unwinding.