Abstract: An optical disk of the invention comprises a substrate of an aromatic polycarbonate obtained by polymerizing one or two monomers polymerized through carbonate linkages and a recording layer coated thereon, said recording layer being recordable and readable by a laser beam,the monomer being selected from the group consisting of:(a-1) 1,1'-bis-(4-hydroxyphenyl)-p-diisopropylbenzene(a-2) 1,1'-bis-(4-hydroxyphenyl)-m-diisopropylbenzene,(b-1) 2,2-bis-(4-hydroxyphenyl)propane,(b-2) 2,2-bis-(4-hydroxyphenyl)butane,(b-3) 2,2-bis-(4-hydroxyphenyl)-4-methylpentane,(b-4) 2,2-bis-(4-hydroxyphenyl)octane,(b-5) 1,1-bis-(4-hydroxyphenyl)cyclohexane,(b-6) 4,4'-dihydroxy-2,2,2-triphenylethane,(b-7) 2,2-bis-(4-hydroxy-3-methylphenyl)propane,(b-8) 2,2-bis-(4-hydroxy-3-isopropylphenyl)propane,(b-9) 2,2-bis-(4-hydroxy-3-sec.