Abstract: An information recording medium in which bottoms of a guide groove and a pit array formed on a disc substrate are allocated on a same flat plane and shaped in flat. Further, in a transition area from a pit array to a guide groove or from a guide groove to a pit array, the information recording medium is provided with an intermediate area composed of a pit array of which height changes from a height between a bottom and a side of a groove to another height between the bottom and a side of the pit array.

Abstract: An optical disc of a thicker supporting section and a thinner recording section is characterized by: a reinforcement section of a predetermined width which overlaps a supporting section and a recording section. With the reinforcement section, the structure of the optical disc is strengthened, and the resonant frequency of the optical disc is raised, so that the vibration of the optical disc is suppressed and the disc is suitable for high speed (16× up) reading/writing. The optical disc comprises: a circular opening disposed in the center of the optical disc; an annular recording section; an annular supporting section disposed between the annular recording section and the circular opening, wherein the annular supporting section is thicker than the annular recording section; and an annular reinforcement section which is disposed on one of the two sides of the optical disc and overlaps the annular supporting section and the annular recording section.