PURPOSE: To obtain a silicone rubber elastomer applicable to wider use by improving its faults, i.e., gas permeability, friction coefficient, etc., without loosing the strong points of silicone rubber.

CONSTITUTION: There is provided a silicone rubber elastomer in which a polyparaxylylene film is formed on the surface of an organopolysiloxane rubber elastomer according to the vapor phase deposition polymerization method. The mechanism of vapor deposition of polyparaxylylene is composed of three processes as shown in the figure; (A) The first process for vaporization of a solid dimer, diparaxylylene as the raw material. (B) The second process for generation of diradical paraxylylene by thermal decomposition of the dimer. (C) The third process for formation of a film of diradical paraxylylene on a base. Since the film formation is carried out according to the vapor phase polymerization method, conformal coating is possible even on a fine part or a complicated-shape part. Further, this method is characteristically, e.g. free from thermal damage to the base since the vapor deposition is carried out at room temperatures.