A lens barrel that reinforces a connecting part between a movable lens barrel and a fixed barrel, without requiring a new drive source, is disclosed. The lens barrel includes: a rotary barrel fitted in a fixed barrel; a cam mechanism for connecting the rotary barrel and the fixed barrel; and a ring member. The fixed barrel includes an engagement section and a rotary drive mechanism for revolving the ring member. The rotary drive mechanism locates the ring member to an engagement-enabling position when a connection by the cam mechanism reaches a predetermined position, directing the connection from a first end to a second end of an idle revolving area, the first end continuing to an advancement/retreat movement area; and to a release position, when the connection by the cam mechanism is located at the first end of the idle revolving area.