There is provided a backlight unit. The backlight unit includes a light guiding plate, a light source module including a substrate provided with a circuit wiring and a plurality of light emitting diode (LED) blocks each including one or more LED mounted on the substrate to be positioned vertically with respect to the substrate, the one or more LED being disposed to face a side surface of the light guiding plate, a bottom chassis including a base and a sidewall upwardly extending from a circumference of the base, and accommodating the light source module and the light guiding plate in such a manner that the one or more LED is disposed to be adjacent to the sidewall, and a driving unit controlling a current signal applied to each of the plurality of LED blocks to thereby control brightness for each LED block.