A lens barrel includes a radially-retractable optical element constituting a part of photographing optical system, and is movable between a photographing position and a radially-retracted position; a biasing device for biasing the radially-retractable optical element toward the photographing position; and a swing member which is rotatable about a rotation axis extending parallel to the optical axis, the swing member being rotated so as to push the radially-retractable optical element against a biasing force of the biasing device to move the radially-retractable optical element to the radially-retracted position. The radially-retractable optical element and the swing member are mutually positioned so that a moving amount of the radially-retractable optical element per unit of rotation angle of the swing member gradually decreases as the radially-retractable optical element moves from the photographing position to the radially-retracted position.