NOVELTY - A peroxide crosslinking-type fluorine-containing elastomer composition contains branched fluorine-containing elastomer and linear fluorine-containing polymer. The branched fluorine-containing elastomer consists of peroxide crosslinkable crosslinking portion, and has number average molecular weight of 1000-300000 and Mark-Houwink gradient of less than 0.6. The linear fluorine-containing polymer has number average molecular weight of 1000-250000 and Mark-Houwink gradient of 0.6 or more.    USE - Peroxide crosslinking-type fluorine-containing elastomer composition used for crosslinking composition for molded article (both claimed). Uses include but are not limited to solar cell board, motor vehicle, aircraft, rocket, vessel, chemical processing plant, foodstuff plant-equipment, nuclear plant-equipment, iron plate processing installation, fuel cell and electronic component.    ADVANTAGE - The peroxide crosslinking-type fluorine-containing elastomer composition has excellent workability and maintains the stability of branched fluorine-containing elastomer by reducing viscosity.    DETAILED DESCRIPTION - A peroxide crosslinking-type fluorine-containing elastomer composition contains branched fluorine-containing elastomer and linear fluorine-containing polymer. The branched fluorine-containing elastomer consists of peroxide crosslinkable crosslinking portion, and has number average molecular weight of 1000-300000 and Mark-Houwink gradient of less than 0.6, when absolute molecular weight and intrinsic viscosity is plotted on Mark-Houwink plot, with absolute molecular weight along x-axis and intrinsic viscosity along y-axis. The linear fluorine-containing polymer has number average molecular weight of 1000-250000 and Mark-Houwink gradient of 0.6 or more, when absolute molecular weight and intrinsic viscosity is plotted on Mark-Houwink plot, with absolute molecular weight along x-axis and intrinsic viscosity along y-axis. An INDEPENDENT CLAIM is included for manufacture of peroxide crosslinking-type fluorine-containing elastomer.