To prevent not only the shearing of a stopper bolt but also the damage of a mating member fixed with the stopper bolt in a stopper device for suppressing the movement of an arm exceeding a set range by causing the arm to collide with the stopper bolt.

On the mating member 11 fixed with the stopper bolt 12, a narrow groove 15 extending from a through hole 13 of the stopper bolt 12 in a collision direction of the arm and getting narrower as coming farther away from the through hole 13 is formed. The device is constituted so that the stopper bolt 12 intrudes from the through hole 13 into the narrow groove 15 while deforming both sides of the narrow groove 15 when it is made to collides with the arm and deforms beyond a predetermined amount. Thus, the shearing of the stopper bolt 12 and the damage of the mating member 11 screwed with the stopper bolt 12 can be prevented.