PURPOSE: To regulate tracking/camber of a rear wheel suspension device by using simple composition.

CONSTITUTION: A shaft-position-adjusting bolt 20 is attached, by the use of nuts 80, 82, to a bracket 1 for use in supporting an arm on a frame, and then a rotary nut 3 equipped eccentrically with a hole 30c relative to its center through which a shaft for supporting the arm is inserted is attached to a ring bracket 22 attached to the end of the shaft-position-adjusting bolt 20 so that the shaft may be movable toward the top/bottom of a car body corresponding to a screwing position of the bolt/nut. Further, the shaft becomes movable toward the front/rear of the car body by the rotary nut 3 making turning motion.