A tetrafluoroethylene/hexafluoropropylene copolymer has improved moldability in melt extrusion molding, especially with significant reduction of defects in high-speed extrusion coating of an electrical wire. The tetrafluoroethylene/hexafluoropropylene copolymer is obtained by polymerization of at least tetrafluoroethylene and hexafluoropropylene selected from the group consisting of tetrafluoroethylene, hexafluoropropylene and a third monomer without mixing with the resin which has the melting point with the difference of 20 degree C. and more from the melting point of the tetrafluoroethylene/hexafluoropropylene copolymer; and has a complex viscosity of from 2.0×I03 to 10.0×I03 Pa*s and a storage modulus of from 0.1 to 3.5 Pa*s in melt viscoelasticity measurement under the condition of atmosphere temperature of 310 degree C. and angular frequency of 0.01 radian/second. The tetrafluoroethylene/hexafluoropropylene copolymer can be used in an electrical wire as a coating on a conductive core.