To provide a threaded fastener tightening device which sucks a threaded fastener at the distal end of a driver bit and tightens the fastener.

The driver bit 3 freely insertable into a suction sleeve is integrally equipped with a screw head guide 6 positioned so as to cover the outer circumference of its distal end portion and to slightly protruding the distal end portion, wherein an external cross-sectional shape of the screw head guide 6 is a substantially triangular form to be fitted in the suction sleeve 4. As the external cross-sectional shape of the screw head guide 6 is the substantially triangular form, three air suction passages are formed inside the suction sleeve 4, allowing the device to suck a screw 2 at the distal end of the driver bit 3 while pressing the head portion of the screw 2 with the screw head guide 6. As center run-out of the driver bit 3 is reduced, in addition, the device can reliably tighten the screw 2 even extremely small in head diameter.