A luminance control circuit for controlling the luminance levels of different colored light sources that lends itself to easy incorporation into display devices is presented. A light emitting diode (LED) substrate includes a plurality of driving thin film transistors (TFTs) including a semiconductor layer deposited on a substrate. A plurality of LEDs for generating lights of different wavelengths is mounted respectively on the plurality of driving TFTs. A plurality of thin film sensors for sensing the luminous intensities of the plurality of LEDs is formed between the plurality of LEDs and the substrate. A luminance control circuit for controlling the driving TFTs has of a plurality of controlling TFTs including a semiconductor layer deposited on the substrate and is connected to the plurality of thin film sensors.