Patent ID: 8258689

Claim:
A lighting apparatus comprising: a metal halide lamp that includes an outer tube, an inner tube provided inside the outer tube, and an arc tube provided inside the inner tube; and an open-type lighting fixture that includes a mirror part having a concave reflection surface inside which the metal halide lamp is disposed, the mirror part reflecting light emitted from the metal halide lamp at the reflection surface such that the reflected light is emitted through an opening of the mirror part, wherein the metal halide lamp is attached to the lighting apparatus by turning an axis of the metal halide lamp in a longitudinal direction as a rotational axis, the outer tube has a cylindrical part and a curved part that is spherical, the curved part is in connection with an end of the cylindrical part in an axial direction thereof on a side of the opening of the mirror part so as to close the end, relational expressions 22≦r≦28, R≦130, and 3.5≦R/r are satisfied, with r denoting a maximum outer diameter [mm] of the curved part in a direction perpendicular to the axial direction, and R denoting an opening diameter [mm] of the mirror part.