Write-once type optical recording medium and fabrication method thereof

To accomplish write-once type optical recording mediums that have excellent recording and reproducing characteristics and producibility and that are capable of being fabricated at low cost. A write-once type optical recording medium has the structure of which an inorganic recording film , a dielectric film , and a light transmission layer have been successively formed on a substrate . The inorganic recording film is composed of a metal film and an oxide film successively formed on the substrate . When light is radiated to the inorganic recording film , oxygen is separated from the oxide film due to the light catalyst effect, resulting in increasing the oxygen concentration on the metal film side and largely varying the optical constant.