(Object) It is possible to make a display area less perceivable to a user. (Means of Achieving the Object) An HUD device (i.e., the HUD device of the practical example 1) is a display device for displaying in a display area a virtual image of at least a part of a sign that moves. The display device includes a displaying system configured to form an image of the sign that moves with light in a region including an image region (i.e., a predetermined region), and to irradiate a front windshield (i.e., transparent/reflective member) with light that forms at least a part of the image, the part of which is in the image region, such that the virtual image of the at least a part of the image is displayed in the display area. The displaying system includes an FPGA 600 (i.e., control device) that is capable of controlling a characteristic of the image in accordance with position of the virtual image relative to the display area. The image sign to be displayed is an indicator mark indicating the presence and location of an object not being viewable through the front display windshield.