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 lamp includes receiving a 3-Dimensional (3D) image, alternately aligning the left-eye image and the right-eye image of the 3D image, and displaying any one of the aligned left- and right-eye images if a display switching signal for switching the 3D image to a 2-Dimensional (2D) image is input. In the displaying step, the backlight lamps are turned on in synchronization with any one of the aligned left- and right-eye images. Accordingly, it is possible to easily view the 3D image as the 2D image.