To hear and see GPS information in real time with hands freed even under a vibrating environment by incorporating a GPS function in a head- mounted display device.

An operating device 2 generates GPS positional information from a GPS source signal received at a satellite signal receiver part 1, and overlaps the GPS positional information with a view field image input from an image input means 6 thereby to obtain a display signal. The generated display signal is sent by the operating device 2 to a head-mounted display device 5 consisting of an LCD display device 3 and a back light source 4, whereby an image is displayed. In a display method of the head-mounted display device 5, the GPS information is projected by a projection lens to a sunglass-type screen, so that the image input means 6, LCD display device 3 and back light source 4 can be simplified.