PURPOSE: To obtain a polymer composition composed of an oligomer having a specified structure, monomers selected from a specified group and an alkyl (meth)acrylate, having a low volume shrinkage factor, excellent in abrasion resistance and transparency and useful as an eyeglass lens, a prism, etc.

CONSTITUTION: This polymer composition contains (A) 20 to 80wt.% oligomer having a structure composed of terminal allyl ester groups and an inner unit derived from a polyvalent carboxylic acid and a polyvalent saturated alcohol and represented by formula I (A is an organic acid residue derived from a polyvalent carboxylic acid of formula II, formula III, etc., respectively having substituent groups at 1,2-, 1,3- or 1,4-sites; x is an integer of 1 to 10; Z is an organic residue derived from a 2 to 30C polyvalent saturated alcohol having X+1 hydroxyl groups), (B) O to 50 wt.% one or more monomers selected from diallyl 1,2-cyclohexanedicarboxylate, diallyl 4-cyclohexene-1,2-dicarboxylate, diallyl endate, etc., and (C) 5 to 40wt.% alkyl (meth)acrylate and exhibits preferably 10 to 20000 op viscosity at 30°C.