PURPOSE: To prevent reverse bend of chain links by forming connection of chain links constituting the link device into two supporting points construction, making one point into a rotation supporting point and providing a cushioning means on another point to constitute the chain link into two supporting points construction on the film side, and always positioning the rotation supporting point on the film side.

CONSTITUTION: Neighboring chain links 4 are connected with a pin at only one position, and if the rotation supporting point 5 is on the film side of a line 8 connecting the other ends of the chain links 4, the chain links 4 are certainly contracted on the film side at contraction of the link device. When the rotation supporting point is only one and the other end are pulled outward, the rotation supporting point can not remain in any area except the connecting line of the both ends. A stopper as a second supporting point 6 is additionally provided on the film side of the present supporting point (first supporting point) 5, and by action of the stopper (second supporting point) 6 the first supporting point is positioned on the film side of the line connecting the other both ends.