To provide a luminaire using a single base discharge lamp as a light source the efficiency of which can be further enhanced.

This luminaire 1 is equipped with the single base discharge lamp 4 having an arc tube 2 and a base 3, and a casing 6 having a reflecting surface 5, and the total light reflectance of the end face 7 of the base 3 near the arc tube 2 and the peripheral surface 8 of the base 3 facing the reflecting surface 5 is not lower than the total reflectance of the reflecting surface 5. Also, the total reflectance of the end face 7 of the base 3 near the arc tube 2 and the peripheral surface 8 of the base 3 facing the reflecting surface 5 is not lower than 85%, and diffuse reflectance is not higher than 10%. In addition, this luminaire is not a type in which the distance between the peripheral surface 8 of the base 3 facing the reflecting surface 5 and the reflecting surface 5 increases as the peripheral surface is apart from the end face 7 of the base 3 near the arc tube 2.