PROBLEM TO BE SOLVED: To provide a metal halide lamp for growing a plant with a single light source, having a high light intensity resembled to a photosynthetic curve, and good uniformity, and hardly causing unevenness in an irradiated surface, and further to provide a lightening instrument for growing the plant. SOLUTION: This metal halide lamp for growing the plant has a spectral energy distribution resembled to the photosynthetic curve referred to the curve efficient for the growth of the plant by forming a reflector of the sealed beam- type metal halide lamp as a dichroic mirror, and laminating a thin film with selective permeability on a glass lens at a front face.
