A retractable barrel includes a rear holder which holds a rear optical element on an axis, the rear holder having a recess; an annular member movable towards and away from the rear holder without rotation; a retractable holder, accommodated within the annular member, which holds a retractable optical element, and being movable between a position where the retractable optical element is aligned with the axis, and a position where the retractable optical element is displaced from the axis; a position controller which controls the annular member and retractable holder to move between an operational position to a retracted position wherein the retractable holder is at the displaced position. A movement path of the retractable holder includes an oblique path extending obliquely to the axis. The recess prevents the rear holder from interfering with the retractable holder.