A back light apparatus includes a back light part which emits light to a liquid crystal display panel, and includes a plurality of LEDs respectively corresponding to a plurality of colors, a detecting part which detects the light emitted from the plurality of the LEDs, a driving part which drives the LEDs to emit, and a controller which controls the driving part to make color ratios substantially equal to a reference value if the reference value is not equal to the color ratio between at least two colors among the plurality of colors of the light detected in the detecting part.