A backlight unit includes a power converter which generates a light driving voltage in response to a voltage control signal with a first level, a plurality of light emitting strings, wherein each of the light emitting strings receives the light driving voltage through a first end thereof, and a controller which generates the voltage control signal. The controller is connected to a second end of at least one of the light emitting strings and detects a level of a signal at the connected second end to detect an operation state of the light emitting strings. The controller generates the voltage control signal with a second level to stop the power converter from generating the light driving voltage when the operation state of the light emitting strings is in an abnormal state.