A backlight device includes a frame, at least one lamp unit each comprising a transformer and a discharge lamp structured into an integral and rigid unit, and also includes a circuit board for lighting the discharge lamp, which is disposed at the back surface of the frame and at which the transformer is mounted at. The transformer of the lamp unit includes: two terminal blocks having terminal pins; a bobbin having a primary winding and first and second secondary windings wound around an outer circumference of the winding core member; a magnetic core; and two lamp connecting terminals attached respectively to the terminal blocks and connected respectively to the first and second secondary windings, wherein the discharge lamp is attached to the transformer with electrodes of the discharge lamp connected directly to the lamp connecting terminals of the transformer, thus forming the lamp unit into an integral structure. |