An image display device and a method for operating the same are disclosed. The method for operating the image display device including a plurality of backlight lamps arranged on upper and lower sides of a rear surface of a display panel includes receiving a 3-Dimensional (3D) image, alternately aligning a left-eye image and a right-eye image of the 3D image, and alternately displaying the aligned left- and right-eye images. In the displaying step, the backlight lamps arranged on the upper side of the panel and the backlight lamps arranged on the lower side of the panel are turned on in a portion of a period of the left-eye image or the right-eye image.