The adhesion enhancement effect of tetraethoxysilane (TEOS) addition to a silica-polyaniline composite film on ITO glass substrate was studied. The composite film was prepared with the silica-polyaniline core-shell composite nanoparticles which were synthesized by a chemical polymerization of polyaniline in a colloidal solution of silica. A small amount of TEOS and acidic water was added to the dispersion solution of composite nanoparticles. The addition of TEOS was intended to increase the adhesion of electrochromic film to substrate without a deterioration of the electrochromic properties such as response time and cycle life. The adhesion of the films was tested by a tape test, and the composite film with TEOS showed a dramatic increase in adhesion to the ITO glass substrate when compared with the film deposited without TEOS. The electrochromic properties of the films were also characterized using the cyclic voltammetry and the optical response measurement.