1. An image display device comprising: a displaying element configured to display a two-dimensional image; an optical panel arranged in front of an image display plane of the displaying element, and configured to form a three-dimensionally viewable image in a front space of the optical panel on the basis of the two-dimensional image; a recognizing element arranged behind the optical panel, and configured to optically recognize a detected object that has entered the front space, through the optical panel; and a position detecting element configured to detect an approach position of the detected object in the front space on the basis of a recognition result of the recognizing element, the image display device characterized in that the recognizing element includes an area sensor which captures an image in the front space through the optical panel; and the position detecting element detects the approach position of the detected object on the basis of a captured image acquired into the area sensor, wherein the recognizing element recognizes reflected light that image light of the two-dimensional image is reflected by the detected object, and wherein the position detecting element detects the approach position of the detected object on the basis of the reflected light and a display position of the two-dimensional image.