An EUV light source apparatus capable of preventing deterioration and/or breakage of a filter for filtering EUV light. The EUV light source apparatus includes an EUV generation chamber in which EUV light is generated; a target material supply unit for supplying a target material into the EUV light generation chamber; a laser source for applying a laser beam to the target material supplied into the EUV light generation chamber to generate plasma; collection optics for collecting EUV light radiated from the plasma; a filter for filtering the EUV light collected by the collection optics; and a filter protecting member provided between the plasma and the filter, for protecting the filter by blocking flying matter flying from the plasma toward the filter.