A head-up display device placed on an upper surface of a dashboard, includes: an object of view arranged in an inside space of the dashboard; an imaging optical system of real specular image for defining a space where a viewer exists and the inside space of the dashboard, the imaging optical system of real specular image including a semitransparent substrate with a plane of symmetry, the imaging optical system of real specular image forming a real image of the object of view in the space of the viewer with light passing through the substrate; and a reflective screen arranged in the space of the viewer, the reflective screen reflecting light beams of the real image of the object of view supplied from the imaging optical system of real specular image to guide the reflected light beams to the viewer, while allowing formation of an image to be seen by the viewer.