Abstract: To a silicone rubber adhesive composition comprising (A) a diorganopolysiloxane containing at least two alkenyl groups in a molecule, (B) a diorganohydrogenpolysiloxane having at least two hydrogen atoms directly attached to silicon atoms in a molecule and a viscosity of about 5 to about 5,000 cs at 25.degree.C., (C) an adhesion modifier compound containing in its molecule a group represented by (RO).sub.3 Si-- or H(RO).sub.2 Si-- wherein R is selected from the group consisting of methyl, ethyl, trifluoroethyl, hexafluoropropyl, and methoxyethyl groups, and (D) a platinum catalyst is added (E) an organic tin compound. The combined use of components (C) and (E) provides he synergistic effect that the resulting adhesive composition can firmly adhere to even polycarbonate and polyphenylene sulfide resins which are known as difficultly bondable resins.