To provide a rotating power transmitting system which can surely protect a noise from a semi-rotation electromagnetic spring clutch.

A rotating power transmitting system for transmitting a rotating power to a rotating shaft, using a spring clutch has a cam 102 to oscillate a mobile plate 5 m, a cam shaft 101 which has a gear 25 to transmit a driving power, a gear 24 to mesh with the gear 25 of the cam shaft 101 and a rotating ax 28 having the spring clutch 23, and has the characteristic that a one way clutch 31, with a lock direction of a rotating in the positive direction of the spring clutch 23 is equipped with either of the gear 25 of the cam shaft 101 or the gear 24 of the rotation ax 28.