There is provided a polymer composition comprising 5 to 100% by mass of a unit (A) of a lactone compound represented by a general formula (1) and 0 to 95% by mass of a unit (B) of (meth)acrylate as constitutional units, wherein the unit (A) of a lactone compound comprises a unit of an (S) isomer represented by a general formula (2) and a unit of an (R) isomer represented by a general formula (3) at a mass ratio of from 70/30 to 30/70; and wherein the polymer composition has a total light scattering loss of not more than 100 dB/km. The polymer composition is excellent in heat resistance and transparency.