A light reflecting substrate comprises at least: an insulating layer and a metal layer disposed in contact with the insulating layer. The total reflectivity of light in the wavelength range of more than 320 nm and not more than 700 nm is not less than 50% and the total reflectivity of light in the wavelength range of 300 nm to 320 nm is not less than 60%. The light reflecting substrate further improves the emission power of the light-emitting device when used as the substrate therefor.