The invention relates to an optical device, a projection optical system, an exposure apparatus, and a method for manufacturing articles. The optical device includes a mirror, and a plurality of actuators configured to deform a shape of a reflecting surface of the mirror. At least some of the plurality of actuators are arranged on a plurality of concentric circles arranged in such a manner that theconcentric circles are arranged denser as positions of the concentric circles are located farther from a center of the reflecting surface of the mirror, and at least some of the plurality of actuators are arranged at equal intervals in circumferential directions of the concentric circles.