A lens apparatus includes an optical system L0 including a plurality of lenses. The optical system L0 is changeable to a first state in which a focal length of the optical system L0 is a first focal length and a second state in which the focal length is a second focal length shorter than the first focal length, by changing one or some of the plurality of lenses. The maximum image heights and maximum angle of views in the first state and the second state are substantially constant and satisfy a predetermined condition.