A graft copolymer having a structure in which a vinyl copolymer segment formed from a vinyl monomer having an acid is suspended in a molecular chain of a polyolefin resin segment via a .beta.-substituted propylene group is obtained, by reaction of polyolefin resin having .beta.-substituted propenyl group as a pendant and a vinyl monomer having an acid, and further a graft copolymer composition containing the same and a molded product thereof are obtained.The obtained graft copolymer, the composition containing the same and the molded product thereof are excellent in adhesive property to a polar material and scratch resistance.