A polymer composition includes a polymer and a flame retardant. The flame retardant includes: at least one nucleic-acid-related substance that is selected from the group consisting of a nucleic acid base, a nucleoside, a nucleotide and a polynucleotide; and/or at least one derivative of the nucleic-acid-related substance. The derivative is selected from the group consisting of: (a) a sulfate, a nitrate, a borate, a hydrochloride or an isocyanurate of the nucleic acid base; (b) a metal salt of the nucleotide; and (c) a compound obtained by substituting an alkyl group having 1 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group or a mercapto group for a hydrogen atom that is bonded to a nitrogen atom of the nucleic acid base, the nucleoside or the nucleotide.