To enable the brakes in both directions with one brake metal in a brake device for generating frictional force for control in a contact surface with a rod by inclining the brake metal, by forming a surface for supporting a support point of inclination of the brake metal into an inclined surface to be slid at a right angle with respect to the shaft.

A brake metal 2 is fitted in a rod 1 which is moved linearly in a brake housing 7 via a guide bush 6 so that it can be inclined a slightly inside of the brake housing 7, and a wedge 4 is also housed in the brake housing 7 movable at right angles with respect to the axis of the rod 1. A support point 3 of the brake metal 2 is supported by an inclined surface 5 of the wedge 4, and the wedge 4 is energized in a direction at a right angle with respect to the shaft of the rod 1 by a brake spring 9 for working to a releasing piston 10 provided at a fork-like end of the wedge 4. Fluid pressure is applied to the piston 10, and the wedge 4 is moved in an opposite direction, while resisting the brake spring 9 so as to release the braking force.