Hybrid surface modification of TiO₂ by plasma polymerization coating was carried out using allylamine and tetraethoxysilane as monomers. In order to evaluate the adhesive strength between the TiO₂ surfaces and deposited polymers, composite specimens prepared with the plasma-coated TiO₂ and epoxy resin was subjected to the tensile strength measurement. The tensile strength of the allylamine-plasma-coated TiO₂ increased with the plasma energy density, and finally approached to the value for the original epoxy without TiO₂. In the photo-reduction reaction of Ag⁺, the catalytic activity of rutyl-type TiO₂, that is almost inert, was improved remarkably by the plasma surface polymerization with allylamine.