PURPOSE: To facilitate the rotation of a mounting screw, brought into an approaching state, by providing a rotary knob part in which a recessed part is formed, a shaft part rotatably and slidably contained therein, a mounting screw part having a knob shaft part to the other end of which a panel is attached, and a spring member to press the shaft part against mounting screw part side.

CONSTITUTION: When a rotary knob part 38 is operated and the recessed part 44 of an annular edge par 42 and the lock part 26 of a shaft part 12 are registered with each other, a shaft part 12 is pressed through the force of a spring member 50 and a protrusion edge part 16 is slid until it brought into contact with an annular edge part 42, and most thereof is exposed from the rotary knob part 38 and the whole of a screw 10 is lengthened. When the rotary knob part 38 is rotated in a pressed state and the recessed part 44 and the lock part 26 are brought into a position where they are not registered with each other, the lock part 26 is brought into contact with the annular edge part 42 and the hole of the screw 10 is shortened. Thus, when the screw 10 for mounting is arranged in the vicinity, only the rotary knob part 38 of the screw 10 for mounting desired to be rotated for control is protruded from the other and easy operation is practicable.