Oriented thin films of polyaniline (emeraldine base) were prepared by the friction transfer method by rubbing solid polyaniline against a glass substrate to form a thin coating film on the substrate. Characterization by polarized ultraviolet-visible-near infrared spectra showed the dichroic property of the films, suggesting that the polyaniline was oriented on the glass substrate. Hydrochloric acid treatment transformed the film into emeraldine salt without loss of orientation. Moreover, the oriented film of emeraldine base could be recovered by aqueous ammonia treatment of the emeraldine salt. The oriented film could also be doped with camphorsulfonic acid.