The present embodiment discloses an interchangeable lens that can be detachably attached to an apparatus body having an image forming surface on which an image is formed, and the interchangeable lens has a magnification conjugate point on a magnification side and a reduction conjugate point on a reduction side. The interchangeable lens includes a focus lens group that can move along an optical axis to adjust a focus at the magnification conjugate point and a flange back distance correction lens group that can move along the optical axis to correct an error in a flange back distance of the interchangeable lens with respect to the image forming surface.