To provide a photo-guide plate for back illumination which reflects the beams of light led in from a narrow end face of a photo-medium with a high gain inside the photo-medium, which emits the beams upon allowing them to pass through a wide surface uniformly, and directs them to the intended point which a person is watching.

An objective lens 62 with refracting function is installed close to a light source 52 or in a single piece structure, and a group of strip surfaces having reflecting function are installed on, or machined in, the rear surface of a photo-medium 60. Each strip surface is formed from a conically curved surface, wherein the concave of the curve is facing the light incident side. The objective lens 62 constitutes a refractive convergence optical system in which the light source 52 and an information image display surface 70 are in conjugate relationship. The strip surfaces are formed from conical surface in which the lens 62 and the point of watching are in the conjugate relationship so that a convergence optical system is configured. Therei a large quantity of light beams from the light source are introduced to the end face by the lens 62, reflected uniformly by a plurality of strip surfaces, emitted from a wire area of surface, and converged onto the point of watching. Accordingly a light-umemissive image display surface installed on the emitting surface of a photo-guide plate can be viewed at intense lumiannce and uniform illuminance.