In a head up display apparatus adapted to be mounted on a head in the goggle type or the head gear type and enable a video image to be observed, wherein an original image is directed to an eyeball through a reflecting optical system to enable the image to be observed, one or more members differing in power depending on the azimuth direction are present in the reflecting optical system, and the members are designed to have an aspherical surface action in the cross-section of at least one azimuth direction.