Abstract: A power-driven screwdriver for use with a motor-driven tool for driving a strip of screws one at a time into a workpiece and having an outer guide frame in which a slide block and a slide plate are slidably mounted. A screw indexing lever is angularly movably mounted on the slide block and has a pin received in a first cam slot having an oblique portion and defined in the outer guide frame and a second cam slot defined in the slide plate. When the motor-driven tool is pushed toward a workpiece, the slide block and the slide plate are slid into the outer guide frame, allowing a screwdriver bit to engage and drive a screw into the workpiece. After the screw has been driven, the motor-driven tool is retracted away from the workpiece, whereupon the slide block and the slide plate are forced to slide out of the outer guide frame under the bias of a spring around the screwdriver bit.