A lens barrel capable of achieving a smooth zoom operation and reducing a driving load at the time of barrel retraction. The lens barrel includes a rectilinear guide cylinder rectilinearly moving in an optical axis direction, and a movable cam cylinder moving in the optical axis direction while rotating relative to the guide cylinder. The guide cylinder is formed at its inner peripheral surface with a cam groove and a rectilinear guide groove that divides the cam groove at a boundary between a retracted region and a photographing region, and is formed with a penetration cam groove extending from the inner peripheral surface to an outer peripheral surface of the guide cylinder. The movable cam cylinder moves in the photographing region while the first pin engages the cam groove, and moves in the retracted region while the second pin engages the penetration cam groove.