Provided is a lens barrel comprising a fixed cylinder; an optical system having a first optical component that moves relative to the fixed cylinder; a first holding frame that holds the first optical component; a guide axle that is connected to the first holding frame and that extends parallel to an optical axis of the optical system; a linear drive unit operable to move the guide axle in the direction of the optical axis and to fix the position of the guide axle; and a holding cylinder that holds the linear drive unit, the holding cylinder being fixed to the fixed cylinder with respect to the direction of the optical axis when the linear drive unit moves the guide axle and moving relative to the fixed cylinder in the direction of the optical axis when the linear drive unit holds the guide axle.