To provide a copolymer that provides a cured product excellent in solvent resistance and adhesion to a substrate.

The graft copolymer includes: a monomer unit corresponding to a vinyl monomer A having a blocked isocyanate group; a monomer unit corresponding to a vinyl monomer B having a carboxyl group or an acid anhydride group; a monomer unit corresponding to a vinyl monomer C having a 3- to 5-membered cyclic ether group; and a monomer unit corresponding to a macromonomer D having a (meth)acryloyloxy group at the terminal of the polymer chain thereof and a weight average molecular weight of 500-30,000, wherein the polymer chain site derived from the macromonomer D constitutes the branch site. The graft copolymer may further include a monomer unit corresponding to a (meth)acrylic acid alkyl ester, an aromatic vinyl compound, and a hydroxyl group-containing monomer.