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 .