In a screwdriver for bone screws, having a handle and rotationally fixedly held thereon a shaft, the free end of which has a non-circular cross section and is insertable in a positively locked manner in a non-circular receiving opening in the head of a bone screw, at least one expander element being mounted so as to be displaceable in the longitudinal direction in the shaft and so as to slide, when displaced in the longitudinal direction, along a slide surface in the area of the free end of the shaft in such a way that it projects laterally over the contour of the shaft, in order to simplify the actuation of the at least one expander element, it is proposed that the at least one expander element be pretensioned by an elastic spring element in the direction towards the free end of the shaft and be retractable against the action of the spring element in the shaft until it no longer projects laterally over the contour of the shaft.