An EUV exposure apparatus is configured to maintain the reflective index of the optical element as high as possible and to minimize the maintenance frequency of the optical element by restraining attachments of released gas particles by degasifying to the optical element. An exposure apparatus is configured to expose a pattern of an original on a substrate by using extreme ultraviolet light. The exposure apparatus includes an optical element configured to receive the extreme ultraviolet light, a barrel configured to support the optical element, a chamber configured to store the barrel, and a partition wall configured outside and around an optical path of the extreme ultraviolet light in the barrel.