A separating agent which combines a high optical resolving power inherent in polysaccharide derivatives with sufficient solvent resistance and a method with which the separating agent can be produced efficiently in short steps. The separating agent for enantiomeric isomers is characterized in that a polymerizable polysaccharide derivative of a polysaccharide derivative having polymerizable functional groups and a polymerizable monomer having polymerizable unsaturated groups are copolymerized with a carrier having polymerizable functional groups to be chemically bound mutually. The separating agent is preferably used for high performance liquid chromatography (HPLC) and has an excellent solvent resistance.