A rotation transfer mechanism of a lens barrel includes a pair of rotatable rings, adjacent ends of which are opposed to each other; an axial-direction projection extending in the rotational axis direction; an axial-direction recess in which the axial-direction projection is positioned; a rotation transfer groove located on an inner peripheral surface of the one of the rotatable rings that has the axial-direction projection, wherein a circumferential position of the rotation transfer groove corresponds to a circumferential position of the axial-direction projection; a driven rotational member having a rotation transfer protrusion engaged in the rotation transfer groove, the rotation transfer protrusion slidably movable in the rotation transfer groove in the rotational axis direction and configured to transmit rotation of the rotatable ring to the driven rotational member; and at least one optical element configured to be driven by the driven rotational member.