An LED backlight device includes a substrate having an optical transparency and an LED thin-film layered structure fixed to a first surface of the substrate. The LED thin-film layered structure is formed of epitaxially grown inorganic material layers as a P-N junction device. An anode electrode and a cathode electrode are formed on the LED thin-film layered structure. An anode driver IC and a cathode driver IC are provided for driving the LED thin-film layered structure. A wiring structure electrically connects the anode driver IC and the anode electrode of the LED thin-film layered structure and electrically connects the cathode driver IC and the cathode electrode of the LED thin-film layered structure. A phosphor is formed on the second surface of the substrate opposite to the first surface.