A lens barrel includes a plurality of lens groups each having at least one lens; a plurality of lens retaining frames which retain a corresponding one of the plurality of lens groups; a telescopic cylinder containing therein the plurality of lens groups and the plurality of lens retaining frames; a lens retaining frame driving device configured to drive at least one of the lens retaining frames; a moving member which moves in a direction along the photographing optical axis; and a position detector configured to detect a change in a position of the moving member, wherein the plurality of lens retaining frames including a retractable lens retaining frame configured to retract the at least another one of the plurality of lens groups from the photographing optical axis to a retracted position out of the telescopic cylinder in the collapsed state.