A braking actuator uses a single cylinder without using a spring to achieve a 3-position operation. A partition plate and an intermediate check plate are affixed within a cylinder at suitable intervals in the axial direction. Inserted movably in the axial direction of the cylinder are a first piston disposed between a pressing lid and the intermediate check plate, a second piston disposed between the intermediate check plate and the partition plate, and a third piston disposed between the partition plate and a pressing lid. A rod which is axially movable within the cylinder has a base end attached to the third piston and a tip end which extends outside from the cylinder through the partition plate, the second piston, the intermediate check plate, the first piston, and the pressing lid. A stopper affixed to a middle portion of the rod moves the first piston or the second piston.