To simply and surely adjust and fix a mechanism to surely prevent the looseness of a screw after adjustment, by continuing threaded engagement in a press-in condition despite before fastening completion after threaded engagement by a deformation absorbing portion, provided on at least one side of a male or female screws.

An eccentric spindle 3 is formed on the other end of a screw head 2, equipped with a hexagonal hole 2-1 on one end part of a resin-made screw 1, and a positioning spindle 4 is provided on the tip part of the eccentric spindle 3. A screw spindle 5, equipped with a leading-in spindle 7, is provided on the opposite side end part to the eccentric spindle 3 of the spindle 4, and a long hole 6, having width (a), is formed in the longitudinal direction of the screw spindle 5. An adjusting member 9, to which the adjusting screw 1 is to be fitted, is mounted on the eccentric spindle 3 portion, consequently, the rotation of the screw 1 changes the position of the adjusting member 9 engaged with the eccentric spindle 3. An outer diameter of the screw spindle 5 is set slightly larger than the valley diameter of a female screw engaging with the screw spindle 5. Consequently, when the adjusting screw 1 is threadedly engaged, the male screw part 5-1 is press-fitted into the female screw, and by the existence of the long hole 6, the screw part 5 is elastically deformed to be firmly joined to the female screw.