To provide effect identical to that in conventional de-metalization process through transmissivity improvement by means of a change in light reflection layer resulting from the shape, pitch, depth, or the like of a rugged structure in an optical medium according to the invention, by solving a problem in that, a conventional de-metalization process requires complex steps such as mask formation and etching, the line width of the reflection layer de-metalized relies on the position accuracy of mask print, making de-metalization process difficult at a nano-level of line width, and etching requires large-scale equipment, requiring time for setting etching conditions and so on.

An optical medium has a simple configuration in which a light reflection layer is disposed on a transparency formation layer formed from a rugged area where a rugged structure is formed and a non-rugged area where no rugged structure is formed. Transmissivity varies with a change in the film thickness of the light reflection layer, resulting from the shape, depth, pitch, or the like of the rugged structure. Its transmissivity is higher than that in the area where no rugged structure is formed.