The chelating resin is an ion-exchange resin. It has been developed as a functional polymer, which selectively catches ions from solution including various metal ions and separates them. It is made of a polymer base of three-dimensional mesh construction, with a functional group that chelate-combines metal ions. Chelating resins are used to treat plating wastewater to remove heavy metals remaining after neutralization and coagulating sedimentation, or to collect metal ions by adsorption from wastewater whose metal-ion concentration is relatively low.