To improve an image forming quality by enhancing the drive force cutoff accuracy of a spring clutch as a rotating drive force transmitting device and further stabilizing a stop timing and a stop position of the resist rollers and document table for an image forming device driven by the spring clutch.

A spring clutch 3 coaxially arranged with a coiled spring and a control ring 3e on the outer peripheral surfaces of an input shaft and an output shaft is structured so that a second lever member 10 engaged with the locking gear 3f of the control ring 3e to stop its rotation rotates the locking gear 3f a specified amount by energizing force by a tension sprint 11 in engaging with the locking gear 3f.