The present invention provides a thermoplastic resin which exhibits excellent heat resistance, high refractive index, low dispersibility and excellent transparency. A phosphorus-containing thermoplastic resin which contains a repeating unit represented by formula (1) and/or a repeating unit represented by formula (2). (In formula (1), each of R1, R2, R3 and R4 independently represents a hydrogen atom, a halogen group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted thioalkoxy group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylcarbonyl group, or a substituted or unsubstituted aminocarbonyl group; and Q represents a diol compound residue.) (In formula (2), each of R5 and R6 independently represents a hydrogen atom, a halogen group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted thioalkoxy group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylcarbonyl group, or a substituted or unsubstituted aminocarbonyl group; and Q represents a diol compound residue.)