To provide a method for manufacturing a graft copolymer through polymerization of at least one kind of compound among olefins and cycloalkenes with a (meth)acrylate polymer, capable of controlling the content of a (meth) acrylate homopolymer.

The copolymer is manufactured through polymerization of at least one kind of compound among olefins and cycloalkenes with a (meth) acrylate polymer having an unsaturated bond in the presence of a polymerization catalyst. The polymerization catalyst contains at least (B) one compound selected from the group consisting of (A) a transition metal compound, (B-1) a compound forming an ion pair by reacting with the (A) transition metal compound, (B-2) an organic aluminum oxy compound, and (B-3) an organic metal compound.