an exposure apparatus for illuminating a pattern with light from a light source and for exposing a predetermined surface with light from the pattern includes a projection optical system for projecting the pattern onto the predetermined surface , the projection optical system having at least one optical element having optical surfaces , and a gas supplying device for locally supplying a gas to the at least one optical element . in one aspect , the gas supplying device directly blows the gas toward one of the optical surfaces of the at least one optical element , which is closest to the predetermined surface , from the predetermined surface side .