Rubber composition for a plasma processing apparatus sealant

[SOLUTION] (a) a crosslinkable fluororubber, relative to the rubber (a) 100 parts by weight of, has (b) a divalent perfluoropolyether structure or divalent perfluoroalkylene structure, terminal or side chain and at least an organic silicon compound (c) reactive fluorine-based compound having two or more hydrosilyl groups and an additional reactive alkenyl groups in (excluding crosslinkable fluororubber (a)), the (C) in a molecule having two or more hydrosilyl groups, in an amount of 1 to 10 parts by weight and the compound (b) capable addition reaction with the alkenyl groups in the reactive organic silicon compound in total, further, the rubber composition comprising a vulcanizing agent, a co-crosslinking agent if necessary, and the composition was the primary vulcanization molding, and then the unreacted components in the molded body by secondary vulcanization in a vacuum oven a plasma processing apparatus for sealing material made by reducing the quantity of released gas as unreacted components. [Effect] In particular, in semiconductor manufacturing processes, stickiness and fixed with a partner member is less likely to occur even when used for a long time continuously at a high temperature, there is no problem of particle generation, no contamination by outgassing, low cost the plasma processing apparatus for the sealing material is provided in a possible manufacturing.