An exposure apparatus which projects and transfers a pattern formed on a mask to a substrate using exposure light includes a stage, an optical system, and a gas stream forming mechanism which forms a stream of inert gas in an optical path space including a space which is located between the stage and the optical system and through which the exposure light passes. In addition, a member forms a predetermined space between the optical path space and a peripheral space outside the optical path space in the exposure apparatus, and a gas supply mechanism supplies the inert gas into the predetermined space.