A parking brake reduced in size and simplified is installed on a rod-protruding side of a cylinder of a caliper braking device. A second piston is provided within the second cylinder that is coaxially coupled with the cylinder and movable coaxially relative to the rod. A one-way clutch is provided to switch ON/OFF due to a releasing/pressing by the second piston with respect to a switch disposed facing a cylinder side surface of the second piston. A parking operation auxiliary spring is provided on the side of the cylinder within a second cylinder, and a manual release piston is provided in a space of the second cylinder. A parking release lever pushes a manual release rod at the tip end of the manual release piston, pushing the second piston in the direction of retraction of the rod, at the same time as the manual release rod pushes into the rod.