An exposure apparatus includes a projection optical system that projects a pattern of a reticle onto a wafer, a vacuum chamber in which the projection optical system is disposed, a partition provided in the vacuum chamber and dividing a first space (which is a space where at least a portion of the projection optical system exists) and a second space (which is a space other than the first space) from each other, a gas supplying unit that supplies gas to the first space, and a sealant that reduces flow of the gas supplied through a pipe into the second space.