A backlight unit includes a main light-emitting diode (“LED”) array, a sub LED array, an LED driver which individually controls an on-off operation of the main LED array and an on-off operation of the sub LED array and includes a first switch, a second switch, a third switch, a fourth switch, a sub switch control unit, and a main switch control unit, and a direct current (“DC”)/DC converter unit which receives an input voltage and provides a DC voltage to the LED driver where the sub switch control unit controls the first and third switches so that one of the first and third switches is turned on and the other is turned off, and the main switch control unit controls the second and fourth switches so that one of the second and fourth switches is turned on and the other is turned off.