To prevent the damage of a gatepost or an automobile because a chain comes off when excessive tensile force is applied to the chain stretched between lifting members of the gateposts of a parking garage.

The gatepost of the parking garage is provided with the lifting member 25 lifted by a driving device, and a U-shaped cutout 11 extending almost in a horizontal direction is formed at the tip part of a hook 10 projecting horizontally from the lifting member. One end of the chain 18 is inserted in the U-shaped cutout 11, and an open part of the U-shaped cutout is provided with a stopper member for preventing the chain from being detached from the U-shaped cutout in a normal service state but detaching the chain from the U-shaped cutout if predetermined tensile force or more is applied to the chain. The stopper member may be a rectangular plate 12 with a notch 12a formed at an intermediate part and with both ends fitted to the tip face of the hook to straddle the open part of the U-shaped cutout, may be a plate spring with one end covering the open part of the U-shaped cutout and with the other end fitted to the tip face of the hook, or may be a ball provided at the open part of the U-shaped cutout and energized by a spring.