To provide a wide angle of a visibility and to obtain a desired mechanical strength by arranging and embedding a cylindrical lens having a higher refractive index than a transparent plate in a direction orthogonal to a bus on the light incident surface of a transparent plate.

The cylindrical lens 103 being a refractive index distribution type medium is provided on the incident surface side of a lenticular lens plate 101b, the emitting surface 105 of the plate 101b is worked to be flat and a clad part 107 formed of material whose refractive index is lower than the center refractive index of the lens 103 is provided in between. A main light beam G out of respective luminous fluxes R, G and B deflected by a Fresnel lens plate 101a is made incident in parallel with the optical axis of the plate 101b, and the main light beams R and B are made incident at a centralization angle with respect to the optical axis. Then, the appropriate angle of visibility that the respective luminous fluxes R, G and B being the incident luminous flux are diffused over a wide visual field range by the refracting action by the refractive index distribution inside the lens 103 and the refracting action by the difference of the refractive index of the surface 105 is secured.