A lens barrel includes an optical system including a first lens group having at least one lens; a cam frame including a first cam groove; and a first movable frame including a first cam follower engaged with the first cam groove. When the first movable frame relatively rotates with respect to the cam frame, the first movable frame relatively moves with respect to the cam frame in an optical axis direction together with the first lens group. A region of the first cam groove, through which the first cam follower passes when a focal distance of the optical system is changed from a wide-angle end to a tele end includes first and second regions adjacent to each other. The first region has a groove width narrower than that of the second region.