Abstract: A clutch 100 includes: an internal gear 3 that includes a gear tooth formed on an inner-surface side thereof; a sun gear 4 that is disposed on the same shaft at a central portion of the inner side of the internal gear 3; one or more planetary gears 5 that are disposed between an outer circumferential surface of the sun gear 4 and an inner surface of the internal gear 3; a carrier 6 that is provided with a boss portion 6a that supports rotatably the planetary gear 5; an electromagnetic coil portion 7; a rotation limit member 8 that is slidably inserted into the electromagnetic coil portion 7 in a shaft direction and selectively disposed at a first position for limiting rotation of the internal gear 3 or the sun gear 4 or at a second position for permitting the rotations of the internal gear 3 and the sun gear 4; and an elastic member 9 that is disposed between the electromagnetic coil portion 7 and the first flange portion 8b of the rotation limit member 8.