A reflective projection optical system comprises a first optical unit having at least one reflecting optical element, and a second optical unit having at least one reflecting optical element. A focal point on the second surface side of the first optical unit approximately agrees with a focal point on the first surface side of the second optical unit. An angle between a normal to the first surface and a principal ray of the illumination beam incident to the first surface is larger than a value of arcsine of a numerical aperture on the first surface side of the reflective projection optical system. All the optical elements in the projection optical system are located outside an extension surface of a ray group defining an outer edge of the illumination beam incident to the first surface.