1. A liquid crystal display (LCD) device, comprising: a backlight unit having a plurality of division regions, each division region corresponding to a plurality of light sources; an LCD panel for displaying a plurality of division images divided from an entire image of one frame, the division images corresponding to the division regions, respectively; an image dividing part to divide the entire image of one frame into the plurality of division images corresponding to the number of the division regions; a first calculator to calculate average brightness of the entire image of one frame; a second calculator to calculate average brightness of each division image; a backlight drive signal generator to compare the average brightness of the entire image of one frame with the average brightness of each division image and to generate a plurality of backlight drive signals for adjusting brightness of the plurality of division regions within one frame according to the comparing result; and a backlight driver to generate a plurality of backlight drive voltages for adjusting the brightness of the plurality of division regions in response to the plurality of backlight drive signals such that light having the adjusted brightness is emitted from the plurality of light sources included in each division region, wherein the backlight drive signal generator generates a backlight drive signal for adjusting a brightness brighter than or the same as the average brightness of the division image when the average brightness of the division image is greater than the average brightness of the entire image of one frame.