Abstract: An extreme ultraviolet light source apparatus comprises a target supply unit supplying a target into a vacuum chamber, a laser oscillator outputting a laser light into the vacuum chamber, a collector mirror outputting an extreme ultraviolet light outside by reflecting the extreme ultraviolet light emitted from the target being ionized as a plasma by irradiation with the laser light at a plasma luminescence point in the vacuum chamber, and an ion debris removal unit at least a part of which is located in an obscuration region including the plasma luminescence point.