An optical apparatus includes an image taking optical system that includes a first lens unit arranged on a most object side and a second lens unit movable in an optical axis direction further on an image surface side than the first lens unit, a first lens barrel that holds the first lens unit, a second lens barrel that is combined with the first lens barrel and houses the second lens unit so that the unit is movable, and a control unit that is arranged around an outer periphery of the second lens barrel and includes an operation member, which is operated in order to instruct driving of the second lens unit, and an electric component for controlling the driving of the second lens unit according to the operation of the operation member, in which a maximum outer diameter of the first lens unit is larger than a minimum inner diameter of the control unit.