Clutch, motor, and power window device

A clutch comprising:

• an annular collar having an inner circumferential surface;
• a driving-side rotor configured to be driven and rotated;
• a driven-side rotor having a control surface opposed to the inner circumferential surface of the collar;
• a rolling element located between the control surface and the collar and having two opposite sides in a circumferential direction of the collar;
• and
• a retainer including two circumferential holders holding the two opposite sides of the rolling element, which is located between the control surface and the collar, wherein the retainer is configured to rotate in the circumferential direction, wherein
• the clutch is configured, when the driving-side rotor is in a non-driven-rotated state, to prevent rotation of the driven-side rotor by setting the rolling element in a lock state in which the rolling element is held by the control surface and the collar,
• the clutch is configured so that when the driving-side rotor is driven and rotated in the lock state, the driving-side rotor pushes the rolling element via the two circumferential holders in a rotation direction to release the rolling element from the lock state, and
• each of the two circumferential holders includes a guide portion configured to guide the rolling element toward a radially inner side of the collar when the rolling element is released from the lock state.