To provide a rotary drive force transmission device with a simple structure, capable of both direction rotary force transmission and both direction over running.

A rotary drive force transmission device is composed of a drive plate 5, having a cam 5b, a driven plate shaft 7 turnably fitted to the outer periphery of the drive plate 5, a ball 6 inserted in the cam 5b and an engagingly locking plate 4 for regulating the ball position. When the drive plate 5 is rotated to the right and to the left, a rotary force is transmitted to the driven plate 8 via the ball 6. When the driven plate 8 is rotated with higher speed than the drive plate 5, regulation is carried out by the engagingly locking plate 4 so as not to move the ball 6 to the position where the drive plate 5 is driven reversely by the driven plate 8 and a normal over running is carried out.