In a backlight device and a driving method thereof, a voltage controller controls a voltage level of a first input voltage in response to a dimming signal to output a second input voltage. A pulse generator receives the second input voltage from the voltage controller and generates a pulse signal having a duty ratio corresponding to the dimming signal and a high voltage level corresponding to the second input voltage. An inverter generates a lamp driving signal based on the pulse signal. At least one lamp included in the backlight device is turned on or turned off in response to a lamp driving signal to adjust luminance of the backlight device.