According to one embodiment, a transmission optical system which guides light in a nearly parallel beam state emitted from an optical outlet port of a light source, to an optical inlet port of an exposure apparatus body and which injects the light in the nearly parallel beam state into the optical inlet port is provided with a condensing optical system which keeps the optical outlet port and the optical inlet port in an optical Fourier transform relation, and an angle distribution providing element which is arranged in an optical path between the optical outlet port and the condensing optical system and which provides an emergent beam with an angle distribution in a range larger than a range of an angle distribution of an incident beam.