Abstract: In a power transmitting apparatus for transmitting power from the driving side to the driven side using a fluid joint means, a rolling bearing clutch including an inner ring, an outer ring and a plurality of rollers interposed between track surfaces of the outer periphery of the inner ring and the inner periphery of the outer ring is disposed between the driving side and the driven side for performing ON/OFF operations by allowing the track surfaces of the inner ring and the outer ring to move near to each other or away from each other, and the driving side and the driven side are mechanically connected to each other without any fluid joint means interposed therebetween by shifting the bearing clutch to the ON position whereby a power transmitting efficiency can be improved without any slip loss by mechanically connecting the driving side to the driven side with a clutch mechanism.