An image display system includes: a plurality of image supply devices each having an image display section, and an image transmission section adapted to generate a supply image and to externally transmit the supply image; and an image display device capable of dividing a common screen area into one or more screen areas, and of displaying the supply image supplied from each of the image supply devices in the one or more screen areas, wherein each of the image supply devices displays a common screen area operating image to operate a display state of the common screen area in the image display section, and supplies a display image of the image display section to the image display device as the supply image, and the image display device changes the display state of the common screen area in accordance with an operation in each of the image supply devices.