An image display device controls a screen luminance to an appropriate value in response to switching of a display mode, thereby displaying each of television broadcast program images and graphic user interface images (including an electronic program guide, and a variety of setting menus) in an easy-to-see and power-saving manner. The image display device switches between a mode of displaying the television image and a mode of displaying the graphic user interface image. In response to the mode switching instruction, the device controls variably luminance intensity of a backlight source, thereby providing a screen luminance appropriate for each mode.