An object of the present invention is to provide a head-up display apparatus and a cover-mirror unit used for the same.A movable member 3′ of the cover-mirror unit stands up along a flat inner wall 1a1 of a housing 1a when the head-up display apparatus is in use, and lie down to cover an opening of the housing 1a when the head-up display apparatus is not in use for carrying out an up/down operation. In particular, through the down operation, by a link mechanism, a bottom end of the movable member is gradually moved upward by following the inner wall 1a1 of the housing 1a. Therefore, though the movable member 3′ stands up along the inner wall 1a1 of the housing 1a when the head-up display apparatus is in use, the movable member 3′ never interferes with the inner wall 1a1 through the up/down operation.