PURPOSE: To provide a polymer blend based on comb-shaped polymers.

CONSTITUTION: There is provided a blend being a compatibilized blend of a major amount of at least one synthetic base matrix resin with a comb-shaped copolymer of a polymerizable olefinically unsaturated monomer with a macromolecular monomer of a polylactone, wherein the comb-shaped copolymer has a hydrocarbon backbone, and the macromolecular monomer of the polylactone is represented by the formula: R-(M)m-Z (wherein M represents at least one type of a polyester repeating unit of the ring-opened lactone; m is an integer of 2 to about 500; and Z is a terminal group obtained from ring opening polymerization or a coupling reaction).