PURPOSE: To easily and simply separate a rock sandwitched and stuck into the interval of grizzly bars without interrupting an operation when the rock is sandwitched and stuck between the grizzly bars during running by joining the tip of a piston rod to a stopper with a pin around a vertical axis and tightly providing a hydraulic cylinder in a movable frame.

CONSTITUTION: In a vibrating feeder 20 fitted with a grizzly wherein a plurality of pieces of grizzly bars 26 are arranged in parallel toward the advancing direction of supplied rocks, one end of the grizzly bars 26 is supported by pins via bearings 27 to form the movable bars freely turnable in the horizontal direction. Stoppers 28 are provided projectingly in the lower parts of the other hand and also compression coil springs 50 are repulsively fitted between the respective stoppers 28. The tips of a piston rod 40a are connected to the movable bar 26M of the outermost side. A hydraulic cylinder 40 is arranged in a movable frame 22.