A liquid crystal display device includes a liquid crystal display panel having a gate line sequentially selected by a gate pulse and a plurality of light sources which are sequentially turned on along a scan direction of the gate line. The plurality of light sources are turned on with a first level of brightness during a white turn-on period, and turned on with a second level of brightness during a gray turn-on period. The second level of brightness is lower than the first level of brightness to irradiate the liquid crystal display panel with light. As a result, a life span of the plurality of light sources may be extended.