PURPOSE: To perform the functions of several motor graders by only one grader by allowing the side wing device of the motor grader to freely move vertically, laterally, and in rocking manner along the front and rear directions of a car body.

CONSTITUTION: Paired moving rails 2 are provided in parallel and horizontally on one side and vertical position of a car body 1, a front bracket 4 is slidably fitted into the rails 2, and the bracket 4 is fixed to the moving rails 2 by a stopper 5. A bracket 8 is attached in a vertically slidable manner to the tip of the front bracket 4 by an oil-pressure cylinder 13, and one end of a wing 12 is rotatably attached to the bracket 8 in a vertically rocking manner and in a rotatable manner in the back and forth directions. The tip of the wing 12 is connected with the car body 1 by means of an expandible hollow rod 35. Thus, the wing 12 attached to the side of the car body 1 can work not only as a side wing mechanism but also as a Mac-Lane mechanism.