PURPOSE: To achieve a compact designing and a simplification of a loading/ unloading apparatus along with a shortening of tightening operation time by screwing a male type tightening member having a fitting recess part down securely into a head thread head of a stud bolt beforehand.

CONSTITUTION: A male type tightening member 11 is fixed on the head of a stud bolt 3 screwed down on a flange 33 beforehand. As a tightening rod 10 is lowered toward the male type tightening member 11 fixed on the head of the stud bolt 3, a male member 19 of the male type tightening member 11 advances into a female type tightening member 12 at the lower end of a tightening rod 10. As a result, a fitting ball 14 within the female type tightening member 12 is fitted between an internal wall of an outer cylinder member 13 and a fitting recess part 20 of the male member 19 with a loading/unloading mechanism to allow the tightening of the male type tightening member 11 on a bolt hanging part at a single action. The outer cylinder member 13 moves upward by compressed air to release the fitting of the fitting ball 14 thereby enabling releasing of the fitting of the male type tightening member 11 immediately.