Synthesis and polymerization of 1,1-bis(phenoxycarbonyl)-2-vinylcyclopropane (2) were carried out. The new monomer 2 afforded a 1,5-addition polymer in good conversion by radical initiation. The polymers exhibit T(g) as 76-84-degrees-C and T(d) as 361-377-degrees-C. 2 showed a positive volume change (+6.77%) on polymerization. This could be explained by the facts that the molecular weight of 2 is relatively large and 2 is crystalline at ambient temperature, which means the monomer is already compressed. The compositions of the 1,5-adduct, molecular weights, and volume expansion ratios decreased with increasing reaction temperature or by using solvent in the polymerization. An unknown unit from a side reaction in the polymer might consist of a cyclobutane skeleton.