An extreme ultra violet light source apparatus prevents debris staying and accumulating within a chamber from contaminating the chamber and deteriorating the performance of an important optical component. The extreme ultra violet light source apparatus includes: a chamber in which extreme ultra violet light is generated; a driver laser for applying a laser beam to a target supplied to a predetermined position within the chamber to generate plasma; a collector mirror provided within the chamber, for collecting and outputting the extreme ultra violet light radiated from the plasma; an exhaust path communicating with the chamber and connected to an exhausting device, for maintaining an interior of the chamber at a certain pressure; a catching chamber provided in the exhaust path, for catching debris generated from the plasma; and a collecting unit for collecting the caught debris out of the chamber.