An optical member 7 is bonded, at its rear side 7b, to a holographic stereogram 6. The front side 7a of the optical member 7 consists of parallel triangular prisms. Illumination light 9 is applied to the front surface 7a of the optical member 7 at a predetermined angle of, for example, 60. The optical member 7 is made of, for example, optical glass or transparent plastic. Each triangular prism has an incidence surface 8, to which the illumination light is applied at right angles. The illumination light is applied to the interface 22 between the optical member 7 and the holographic stereogram 6, at an incidence angle of, for example, 60, thereby to suppress surface reflection of the illumination light 9 at the interface 22.