To drive drill screws with a washer straight at the exact positions in fastening corrugated sheet to aggregate with the screws.

A rotary tool head 3 has a cylindrical support member extending, in a fixed position, concentrically with a driver bit 5, and the support member supports a cylindrical slider 7 that freely slides on it. The slider 7 is urged forwardly by a coil spring 8. The slider 7 has a square-holed holder portion 16 in which a washer B on a screw A can be releasably inserted against rotation, and has at its tip an engagement portion 18 adapted to fit a corrugation of a corrugated sheet D.