An ECU as a vehicle device includes an image generation unit that generates an image in a predetermined reference coordinate system, a viewpoint position identification unit that identifies a viewpoint position of a driver; a superimposed position identification unit that identifies a display position at which the image is displayed within an eyesight of the driver; an image conversion unit that generates a converted image obtained by converting the image into a coordinate system having the viewpoint position of the driver as a reference point; and a notification unit that displays a display image falling within the converted image so as to be superimposed on the eyesight of the driver with the projection device.