Poly(p-phenylene terephthalamide) (PPTA) was prepared on a transparent indium-tin electrode as a mechanically stable film by electrolysis of a dimethylsulfoxide solution containing PPTA polyanions. The PPTA film was electroactive because of its ionic conductivity. When an aniline derivative, o-phenylenediamine, was electro-oxidized using the PPTA film-covered electrode, the film captured the red oligomer species and the polymerizing solution was barely colored by the species. The oligomer concentrating effect of the film enhanced the polymerization efficiency of o-phenylenediamine. Further, polyaniline was electrodeposited on the orange PPTA film. The composite film showed three-color electrochromism : orange (-0.4 V), green (+0.4 V), and violet (+1.2 V).