A lens barrel includes a rotatable ring, an outer annular member which is non-rotatable and supports the rotatable ring inside the outer annular member, and an optical element movable along the optical axis by a rotation of the rotatable ring; an advancing/retracting mechanism configured to move the rotatable ring along the optical axis between movement limits of the rotatable ring; a circumferential groove located on the inner peripheral surface of the outer annular member or the outer peripheral surface of the rotatable ring; and a rotation-guiding projection located on the inner peripheral surface of the outer annular member or the outer peripheral surface of the rotatable ring. The rotation-guiding projection is engaged in the circumferential groove such that the rotatable ring is rotatable without moving along the optical axis when the rotatable ring is moved to the front movement limit by the advancing/retracting mechanism.