PROBLEM TO BE SOLVED: To provide a head-mounted display device which enables a user to simultaneously view the real image of a matter in the direction of a visual field and information not appearing to the appearance of the matter, without user's moving the sight lines.SOLUTION: The head-mounted display device which enables a user to simultaneously view an image and an outside scene comprises: a superimposition information generator which generates superimposition information being information to superimpose and display invisible information being information not appearing to the appearance of a matter, onto the matter included in the outside scene； and an image display for causing the user to view the superimposition information as an image.
