A head-up display device includes a housing, a guiding base, a projecting board assembly, a protecting cover and a driving mechanism. The projecting board assembly is movably arranged at the guiding base. The driving mechanism includes a link, a lever, and a drive wheel. A front end of the link is pivotally connected to the protecting cover, and a rear end of the link is engaged with the drive wheel. A lower end of the lever is pivotally connected to the projecting board assembly. The drive wheel is rotatable and can be selectively engaged with the lever. The rotation of the drive wheel can drive the link and the lever to move and thus drive the protecting cover and the projecting board assembly to move. Therefore, the driving mechanism can be more easily arranged, so as to simplify the structure and reduce cost.