An LED luminaire is provided with a light emitting module composed of plural kinds of LEDs emitting lights of different colors, a lens unit having a lens for diffusing the mixed-color light from the light emitting module, a light output controller for controlling electric current fed to each of the LEDs, and a light sensor for sensing the light from the light emitting module. The light output controller performs feedback control on the electric current fed to each of the LEDs based upon light levels of the sensed light, so that the light emitted from the light emitting module has desired chromaticity. The lens unit contains a light guide for guiding the light from the lens to the light sensor and can guide the light from the light emitting module to the light sensor with a high efficiency.