A zoom lens barrel assembly includes an operating barrel formed with a zooming cam operative to perform zooming and focusing while turning, an inner movable barrel fixedly holding a front lens group and formed with a focusing cam which is movable axially only, an intermediate barrel capable of turning relatively to the inner movable barrel within a specified extent of angular interval, and a clutch mechanism operative to couple the intermediate barrel, during zooming, to the inner movable barrel together to restrain the intermediate barrel from turning relatively to the inner movable barrel so as thereby to shift axially the inner movable barrel through the zooming cam following a turn of the operating barrel and, during focusing, to the operating barrel together to restrain the intermediate barrel from turning relatively to the operating barrel and allow the inner movable barrel to turn relatively to the intermediate barrel so as thereby to shift axially the inner movable barrel relatively to the intermediate barrel through the focusing cam following a turn of the operating barrel. The clutch mechanism comprises a clutch lever which is moved to and held in a first position in which the clutch lever restrains a relative turn between the intermediate barrel and inner movable barrel during zooming and moved to a second position in which the clutch lever causes a restraint arm to restraint a relative turn between the operating barrel and intermediate barrel.