Patent ID: 7015161

Claim:
An information recording medium comprising a recording layer on a substrate, said substrate composed of crystallized glass comprising SiO 2 , Al 2 O 3 , MgO and alkali metal oxides and being substantially free of ZnO, wherein the crystallized glass comprises Al 2 O 3 in an amount of 5 to 25 mol % and alkali metal oxides in an amount equal to or less than 5 mol %, main crystals contained in the crystallized glass consist of enstatite and/or its solid solution, thermal expansion coefficient of the crystallized glass at 100 to 300° C. is in the range of from 65×10 −7 to 85×10 −7 /° C., and the substrate has a polished surface with a surface roughness Ra (JIS B0601) equal to or less than 1 nm.