A heat-curable fluoropolyether rubber composition comprising (A) 100 pbw of a straight-chain perfluoropolyether compound having at least two alkenyl groups in a molecule, (B) 1-100 pbw of a reinforcing filler, and (C) 0.1-5 pbw of an organic peroxide is freed from cure inhibition by catalyst poisons, and its cured rubber has improved properties including heat resistance, chemical resistance, solvent resistance, parting property, water repellency, oil repellency and low-temperature properties.