An exposure apparatus and manufacturing methods using the exposure apparatus are disclosed. An exposure apparatus includes a light source system generating light, an optical system controlling and patterning the light, a substrate system on which an exposure process is performed on a substrate by the patterned light, and a control unit controlling the light source system, the optical system and the substrate system. The optical system includes a chamber, a reflection member disposed in the chamber to control the light, and a first on-off valve installed on one side of the chamber opposite to the substrate system. The control unit controls the optical system such that the first on-off valve is opened during the exposure process and is closed during a cleaning process performed to the inside of the chamber.