A circular dividing table includes a brake assembly, in which the piston return spring urges the annular piston with the bottom face of its annular groove. The piston retracts backward and the floating pad return plate contacts the bracket extending inward within the cylindrical bore of the floating pad, thus urging the floating pad backward. Due to the backward displacement of the floating pad, the floating pad is forced to retract from the brake disc. Using a circular dividing table equipped with such a brake assembly, it is possible to release the clamping members forcibly and to make the action of clamping or unclamping precise and conducted with a high responsive speed.