To provide a light source unit capable of collecting DPP divergent light while reducing the adherence of debris to a reflecting surface.

The light source unit is provided with a light source main body for bringing a target material into a plasma state and causing the plasma to emit EUV light, a first reflecting mirror (12a) with a through-hole, a second reflecting mirror (12b) placed in an optical path between the light source main body and the first reflecting mirror, and debris removal mechanisms (25, 26) for removing debris emitted from the light source main body in an optical path between the first and second reflecting mirrors. The light source unit condenses the EUV light to a prescribed position via the reflecting surface of the first reflecting mirror, the reflecting surface of the second reflecting mirror, and the through-hole of the first reflecting mirror.