To provide an adjusting mechanism which can efficiently fit an adjusting bit 12 to an adjusting screw even when the former is brought close to the latter from below and fitted, improves the efficiency of adjusting work, and sets a rotating shaft so as to form a predetermined angle with respect to the adjusting screw, without intersecting each other.

The adjusting mechanism 11 is formed of the adjusting bit 12 fitted to the adjusting screw to transfer rotational driving force to the adjusting screw, an output shaft 13 having the adjusting bit 12 mounted on the tip thereof, and the rotating shaft 14 allowing the output shaft 13 to be connected to one axial end thereof. Then a mounting portion 16 which conforms in shape to an Oldham coupling 15 and allows the Oldham coupling 15 to be mounted thereon, is connected to the output shaft 13, and a mounting portion 17 which conforms in shape to the Oldham coupling 15 and allows the Oldham coupling 15 to be mounted thereon, is connected to the rotating shaft 14, followed by mounting the Oldham coupling 15 to both the mounting portions 16, 17, to thereby connect the output shaft 13 to the rotating shaft 14 via the Oldham coupling 15.