| 摘要 |
PROBLEM TO BE SOLVED: To provide an information recording medium having suitable degree of modulation in a ROM area and free from the deviation of the symmetry, as to the information recording medium provided with a RAM area where recording, reproduction and erasure can be performed and the ROM area where only the reproduction can be performed. SOLUTION: The information recording medium formed by providing a recording layer or the recording layer and a metal layer directly or via a base layer on a light transmissible substrate is characterized in that the information recording medium includes the RAM area 11b where information is recorded, reproduced and erased and the ROM area 11a where information is previously formed as a bit row of recessed and projecting parts and only the reproduction is performed and average film thickness of the recording layer including the metal layer in the ROM area 11a is equal to or thicker than that in the RAM area 11b. |
