PURPOSE: To simplify the setting of a bolt by providing a means which connects the inner cylinder holding the projection side male screw of a stud bolt to an outer cylinder via a transmission means which makes the rotation driving of the outer cylinder as transmission and nontransmission and which makes the transmission means in nontransmission state at the time when the stud bolt is embedded to the regulated height.

CONSTITUTION: When a driving shaft 2 is rotated in the state of the projection side male screw 8 of a stud bolt 7 being held on an inner cylinder 25, an embedded side male screw 9 of the stud bolt 7 is screwed to the female screw 11 of the body to be fitted with a rotation power being transmitted to the inner cylinder 25 from an outer cylinder 22 via a transmission means. When the stud bolt 7 is embedded to the regulated height, then, a steel ball 27 is extruded outside with the R 25c of a socket groove 25a, is inserted into the escape part 26b of a slide collar 26 and the rotation power of the outer cylinder 22 is not transmitted to the inner cylinder 25. Consequently, the embedded at the regulated height is automatically performed without relying on the visual observation of a worker.