PURPOSE: To control the movement of a cage without utilizing mechanical contact friction for providing a high reliability structure in a rotation transmitting device which moves an engaging element by the cage between a driving and driven members to change over a clutch.

CONSTITUTION: A movable cage 12 and fixed cage 13 for holding a sprag 20 are provided between outer and inner rings 1, 2, and a stepping motor 3 is connected to the movable cage 12. The cage 12 is rotated by the stepping motor 3 to hold the sprag 20 in an engaging operative position in the forward and backward directions and a neutral position so that a clutch is turned on and the free running condition is changed over.