Head-up display apparatus and mirror unit for the same

A head-up display apparatus comprising:

• a display device displaying a predetermined image;
• an optical system reflecting said image toward a windshield to be reflected again by the windshield;
• a receiving section being installed in an instrument panel at an opening of the instrument panel for receiving the display device and the optical system;
• a panel cover to cover an opening of the receiving section as the opening of the instrument panel;
• and
• a control mechanism for the optical system, for positioning a part of the optical system from a position in the receiving section to make a car driver sitting on a driver's seat recognize the image when in use, and for positioning the part of the optical system within the receiving section when not in use to make the car driver ignore the image.