PURPOSE: To make it possible to fasten a screw with one hand by providing a driver with a slider moving in the axial direction of the driver, arms with projections which is connected with the slider via a spring plate and a guide fixed on the driver.

CONSTITUTION: A slider 3 capable of being moved in the axial direction is mounted on a driver shaft 2 fixed on a handle 1, and plural numbers of arms 8 with projections 6 are connected with the slider 3 via a spring plate 5. Rubber 9 for fastening a screw is fitted on the tip end of each arm 8, and a guide 4 and a stopper 7 are fixed onto the shaft 2. When the slider 3 is pulled up in such a way that the projections 6 get on the guide 4 at the time of screw fastening, the arms 8 tend to be opened, under which situation the screw is set onto the shaft 2 with hands. Then, the slider 3 is pulled down so as to let the projections 6 come out of the guide 4 for letting the arms 8 be closed by the spring plate 5 so that the screw is anchored with rubber 9. The screw is thereby fastened onto a fitting with one hand.