Abstract: In a head up display apparatus for an automotive vehicle including a projector unit disposed at the ceiling of the automotive vehicle to project display images and a half-mirror reflector unit for reflecting the projected display images to the driver, the height of the half-mirror reflector unit and the angular position of the projector unit are automatically adjusted according to vehicle speed, so that virtual display images can be appropriately seen by the driver ahead of the half-mirror reflector unit along the driver's eye direction variable according to vehicle speed, by use of a relatively small half-mirror reflector unit.