Abstract: A clutch-Brake device, comprising a drive shaft as a driving member, a ring having an inner periphery provided with a surface tapered in an axial direction and coaxially mounted on the drive shaft as a driven member, a plurality of wedges disposed around the drive shaft, each wedge being pivotally mounted on a fulcrum block installed on the inner periphery of the ring, the fulcrum blocks having a tapered surface slidably engaged with the inner peripheral surface of the ring and capable of causing the wedges to move radially toward and away from the drive shaft when the ring is moved axially in one direction or the other. The wedges are adapted to grip the drive shaft when the drive shaft is rotating in one direction and the wedges are moved to come into contact with the drive shaft, so that the ring is driven to rotate with the drive shaft, and to disengage the drive shaft when the drive shaft rotates in the opposite direction, or when the wedges are moved apart from the drive shaft.