Automatic screwdriver

An automatic screwdriver for driving a screw in a horizontal direction comprises a chute for supplying screws with their shanks hanging down, a gate for allowing the screws to be discharged one at a time out of the chute, an index mechanism for carrying a screw discharged from the chute along an angular interval to a catcher disposed in front of a screwdriver bit unit. The index mechanism has a carrier arm angularly movable between a first position in which it receives the screw from the chute and a second position in which the screw is transferred from carrier arm onto the catcher. The screwdriver bit unit comprises a suction pipe for drawing the screw therein from the catcher and a screwdriver bit rotatably disposed in the suction pipe and axially movable for driving the screw into a workpiece. The automatic screwdriver is driven by a pneumatic control system for actuating the gate, the index mechanism, and the screwdriver bit unit.