When the combination of the image signal and contents each having various aspect ratios is displayed on the display with various aspect ratios, an image display device that generates a proper display screen with simple operation or automatically is provided. The image display device of the present invention has a display screen expanding part for expanding a display screen of input image signal in at least one direction of the horizontal direction and the vertical direction based on an expansion ratio; a selecting part for automatically setting the above-mentioned expansion ratio of the above-mentioned display screen expanding part in at least one direction of the horizontal direction and the vertical direction based on information on an aspect ratio of a display, information on an aspect ratio of an image signal, and information on an aspect ratio of contents as an effective section of the above-mentioned image signal; and the above-mentioned display for displaying the display screen of the above-mentioned image signal.