To provide an information recording medium which is prevented from being deformed (bent, distorted) accompanying a change in humidity and is easily manufactured, and an information processor using the same.

In the information recording medium constituted by stacking, on a substrate 20, a recording layer 42 on which information is recorded and from which the information is reproduced by being irradiated with the light beam from a light source, a protective layer 50 having Young's modulus such that a value indicating the distortion degree of the information recording medium 100 in a direction in which the distance between the light source and the recording layer 42 changes falls within a predetermined range with respect to the prescribed change in the ambient humidity under a fixed temperature is stacked on the recording layer 42. Specifically, the Young's modulus of the protective layer 50 is set equal to/higher than 4.7×109[Pa] and equal to/lower than 6.8×109[Pa].

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