The exemplary embodiment suggests an apparatus and a method for driving a light source of a backlight unit. The apparatus for driving the light source of the backlight unit comprises a plurality of LED columns; a power output terminal and feedback terminals connected to the LED columns; and an LED driver sequentially driving the LEDs according to sequentially delayed PWM signals. The LED driver decides an operable number of LED channel based on the signals input through the feedback terminals, and sequentially delays the PWM signals with the phase difference controlled by the number of LED channel.