To provide a lens barrel which can effectively prevent degradation in the quality of a photographic image.

The lens barrel comprises: lens drive parts 321 and 331 configured to drive movable lenses 32 and 33 in the directions of the respective optical axes; a storage part 37 configured to store, for each position of each of the movable lenses in the direction of the optical axis, information about a magnification change rate indicating the relation between the unit amount of movement of the movable lens in the direction of the optical axis and a magnification change of an image of an optical system; and a magnification change information transmission part 36 configured to transmit the information about the magnification change rate corresponding to the position of each of the movable lenses in the direction of the optical axis to a camera body.