PURPOSE: To obtain an information recording medium having high reliability by preventing the generation of foreign matter consisting of a hydrolyzate in a resin substrate even after use over a long period of time.

CONSTITUTION: A substrate is made of polycarbonate or other resin so that the generation of foreign matter of ≥100μm diameter chiefly by the hydrolysis of the resin is prevented when the substrate is allowed to stand for 2.5hr at a temp. below the glass transition temp. of the resin by 5-20°C under the satd. vapor pressure of water at the temp. The objective substrate hating high reliability and the objective information recording medium with the substrate are obtd.