An image display system includes a sensor part, a camera part, and an image display part. The sensor part is configured to sense a presence of a user and output a sensing signal. The camera part is configured to be controlled by the sensing signal, detect an eye direction of the user, and output a detecting signal. The image display part is configured to be operated in one of first, second, and third modes on the basis of the sensing signal and the detecting signal. The sensor part and the camera part are operated independently from the image display part. Power consumption becomes smaller in order of the first mode, the second mode, and the third mode.