1. An image display device comprising: a first display unit having a first image screen for displaying a two-dimensional image; an image transfer panel located on a path of light left from the first image screen; a floating image display means that displays, as a floating image, the light left from the first image screen in a space, the space being located on one side of the image transfer panel opposite to the other side thereof facing the first display unit; a direct-view image display means provided with a second display unit having a second image screen for displaying a two-dimensional image, the direct-view image display means displaying the two-dimensional image displayed on the second image screen as a direct view image; a third display unit configured to display a menu image on which information indicative of a target processing is included; and an image controller that controls the floating image and the direct view image so as to be linked to each other, wherein the image controller comprises: a floating-image control means that displays a given object corresponding to the processing target as the floating image when the information indicative of the target processing is specified on the menu image by a viewer, and displays the floating image such that the given object displayed as the floating image is shifted in a specified first direction from a displayed position of the floating image to the second image screen; and a direct-view image control means that executes the target processing specified by the viewer during or after the shift of the given object, and displays, on the second image screen, a two-dimensional image on which a result of execution of the target processing is displayed, the second image screen is placed at a back of the displayed position of the floating image as being viewed from a view position at which the floating image is viewable, and the image controller is adapted not to carry out the target processing specified by the viewer when the given object is shifted in a second direction different from the specified first direction, further comprising: an alternative second image screen placed in the second direction, the alternative second image screen being different from the second image screen placed in the specified first direction, the image controller further comprising: a second floating image control means that displays the floating image such that the given object displayed as the floating image is shifted in the second direction from the displayed position of the floating image to the alternative second image screen; and a second direct-view image control means that displays, on the alternative second image screen, a two-dimensional image indicative of non-execution of the target processing specified by the viewer.