An HUD device includes a laser scanner that projects laser light carrying a display image, and a screen member that has a plurality of optical elements arrayed in the form of a grating, and diffuses laser light which emanates from the laser scanner and enters the optical elements toward a projection surface. The optical elements have curved surfaces, which take on a convexly curved form as a common curved form, formed as their faces, and diffuse laser light which is emitted to the projection surface from the curved surfaces. A sag quantity from each of surface vertices of the curved surfaces to each of boundaries among the optical elements differs between adjoining optical elements.