The image display device includes a liquid crystal display device having a liquid crystal panel and a backlight and a backlight controller for allowing the backlight of the liquid crystal display device to be bright when environment light is bright and allowing the backlight to be dark when the environment light is dark such that light leak (minimum luminance) which is defined by an extinction ratio of liquid crystal will not grow more than a specified degree. The image display device enables displayed images to be really discernible regardless of brightness of environment light (surrounding light).