To provide a fluorinated elastic copolymer which is excellent in crosslinking reactivity and extrusion moldability and which is curable to obtain a rubber excellent in permanent compression set resistance, base resistance and oil resistance and particularly suitable as a covering material for electric wires. A fluorinated elastic copolymer obtained by copolymerizing tetrafluoroethylene, propylene and optionally another monomer, wherein the molar ratio (a)/(b) of repeating units (a) derived from tetrafluoroethylene to repeating units (b) derived from propylene in the fluorinated elastic copolymer is from 60/40 to 75/25, and repeating units (c) derived from said another monomer is from 0 to 10 mol % in the fluorinated elastic copolymer.