A head-mounted display device includes: an image display unit including an image-light generating unit that generates image light representing an image and emits the image light and a light guide unit that guides the emitted image light to the eye of a user, the image display unit being for causing the user to visually recognize a virtual image; and a control unit that includes an operation surface, is connected to the image display unit, and controls image display by the image display unit. When it is assumed that the user shifts the user's attention from the virtual image, the control unit adjusts the luminance of the image-light generating unit or adjusts the image light generated by the image-light generating unit to reduce the visibility of the virtual image.