The methods for producing macromolecule identifying polymers according to the present invention comprise the steps of polymerizing a starting monomer in an aqueous solution in the presence of a macromolecule, a crosslinking agent, and a radical polymerization initiator to produce a polymer containing the macromolecule in its interior; and removing the macromolecule from the polymer containing the macromolecule to thereby produce the macromolecule identifying polymer having a molecular imprint of the macromolecule. In this method, the crosslinker has a solubility in water at 25.degree. C. of 100% by mass or higher.