To provide an ETFE copolymer and a wire coating resin material capable of forming a coating layer which is excellent in stress cracking resistance under a high temperature and which has a high heat resistance temperature, and an electric wire having a coating layer which is excellent in stress cracking resistance under a high temperature and which has a high heat resistance temperature. A copolymer comprising structural units derived from ethylene, structural units derived from tetrafluoroethylene, and structural units derived from a third monomer, wherein in an elution curve obtained by a temperature rising elution fractionation method with respect to the copolymer, a ratio (L/H) of a proportion (L: area %) of components with elution temperatures of from 190 to 200° C. to a proportion (H: area %) of components with elution temperatures of at least 205° C., and a proportion (M: mol %) of structural units derived from the third monomer based on all structural units of the copolymer, satisfy a relation of log (L/H)/M≥0.90.