In a backlight assembly and a liquid crystal display device using the backlight assembly, a lamp assembly is mounted on a receiving container and includes lamps. The lamps are connected in parallel and are turned on by the power voltage supplied from a lamp driving module. Sensors are disposed in the receiving container to face the lamps, and detect operation state of the lamps to output sensing signals. A voltage cut-off module is disposed outside of the receiving container, provides the lamp driving module with a voltage cut-off signal when at least one of the sensing signals has an amplitude smaller than a reference signal. The deterioration of the lamps may be prevented, and the life expectancy of lamps may be increased.