A cleaning method for an EUV light generation apparatus may include closing a connection portion so that a chamber interior and the interior of an exposure apparatus do not communicate when EUV light is not being generated, supplying an etchant gas for etching debris that has accumulated on a reflective surface of an optical element to the chamber interior in a state where the connection portion is closed, and exhausting the chamber interior using an exhaust apparatus while supplying the etchant gas.