The invention relates to a head-up display device (1) for a vehicle (2) comprising:—an image generating unit (4) generating a primary light beam (7) representing a scene to be displayed, and—an optical projection system (8, 9) for projecting this scene onto an individual (3) situated inside the vehicle, the optical projection system comprising a return mirror (8) having a first face (10) and a second face (11), the first face being turned towards the image generating unit so as to reflect the primary light beam towards a combiner (9) adapted to form an image (16) of the scene visible by the individual. According to the invention, the device comprises at least one element (18) facing the second face of the return mirror and adapted to emit a secondary light beam (19) in the direction of this second face, the secondary light beam being transmitted through the return mirror towards the combiner forming an image (20) of the element visible by the individual.