An elastic fluorocopolymer comprises repeating units (l) based on a fluoromonomer such as tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride or CF2═CF—O—Rf (wherein Rf is a C1-8 saturated perfluoroalkyl group or a perfluoro(alkoxyalkyl) group) and repeating units (m) based on the formula CR1R2═CR3COOCH═CH2 (wherein each of R1 and R2 is a hydrogen atom, a C1-10 alkyl group or a C1-10 alkoxyalkyl group containing an etheric oxygen atom, and R3 is a hydrogen atom, a fluorine atom or a methyl group) in a molar ratio of (m)/((l)+(n))=0.0001 to 0.1. Further, an elastic fluorocopolymer composition comprises (A) the above elastic fluorocopolymer, (B) an unsaturated multifunctional compound and (C) a bivalent metal oxide and/or hydroxide. The elastic fluorocopolymer and the elastic fluorocopolymer composition are excellent in the crosslinkability and can provide a crosslinked rubber thereof excellent in crosslinked rubber properties.