lens barrel 1 a follower defining pin 6 is anchored to the rear end of the outer wall of the focus adjusting cylinder 4 and radially outwardly projects therefrom a first operating ring 7 includes in its forward inner peripheral surface an annular groove 8 in which an inwardly projecting annular member 5 is fitted and a linear groove 10 which is longitudinally slidably engaged by the pin 6 and which extends parallel to the optical axis the first operating ring 7 is fitted at its forward part on the outer peripheral surface of the focus adjusting cylinder 4 the annular engaging member 5 is made of a friction cloth and softly contacts the outer peripheral surface of the focus adjusting cylinder 4 an annular projection 9 is formed on the rear inner peripheral surface of the first operating ring 7 and rotatably matingly engages an annular groove 13 provided in the outer peripheral surface of the second operating ring 11 the annular groove 13 extending at a right angle to the optical axis an annular groove 14 is provided in the rear inner peripheral surface of the second operating ring 11 and contains an annular engaging member 2 which is made of a friction cloth and softly contacts the outer surface of the fixed lens barrel 1 a click ball 15 is fitted in a radial bore provided in the inner peripheral surface of the second operating ring 11 and is urged against the outer peripheral surface of the barrel 1 under the action.