To provide a method for using a bearing as a brake device, a clutch device, and a power transmission device by stopping or returning balls and rollers rollingly and rotatingly moving, which is the characteristic of a bearing, to their original states as intended without losing the functions of the original bearing.

When this device is used as the original bearing, the bearing rotor surrounding the balls and rollers of a rolling bearing rollingly rotates inside an inner race and an outer race along with the balls and rollers. When the rolling rotation is made to stop in the bearing rotor during operation, the balls and the rollers cannot rotate and lose the function of the bearing so as to become an obstruction resistance material. This device is provided by using and applying the above characteristics.