An EUV light source apparatus by which detachment of a chamber or a part of the chamber, movement to a maintenance area, and highly accurate placement relative to projection optics can be performed easily for maintenance of the EUV light source apparatus. The EUV light source apparatus is an apparatus for generating plasma by applying a laser beam to a target material within a chamber and entering EUV light radiated from the plasma into projection optics of exposure equipment, and includes a positioning mechanism for positioning the chamber or a maintenance unit of the chamber in a predetermined location where an optical axis of the collected extreme ultraviolet light and an optical axis of the projection optics of the exposure equipment are aligned, and a movement mechanism for moving the chamber or the maintenance unit of the chamber between the predetermined location and a maintenance area.