To provide a head mount display device, that its display system can be moved in a mount state, it can return to a calibrated position with ease of operation even when the display optical system is moved after calibration.

The head mount display device that exhibits an image to a viewer and has a mobile optical see-through display optical system 1 and amount device 5 that mounts the display optical system onto a head of the viewer, has three or more cameras 2, 3, 4 that photograph and external field visible by the viewer when not mounting the display device. When the display optical system 1 is moved, the display optical system 1 displays the external field image observed at a correction position on the basis of the image photographed by the camera 2 so that the correct position can match by moving the display optical system 1 is a way that the external field visually recognized via the display optical system 1 matches the display image.