In this study, a biological photoelectric transducer based on bacteriorhodopsin (bR) is described. Purple membrane (PM) containing bR are deposited on a TiO₂ electrode surface and electrically oriented. The dried bR purple membrane film is then utilized to investigate the photoelectric response. The latter is induced by charge displacement of bR molecules in the purple membranes. The response is affected by both the wavelength and intensity of the incident light sources. The experimental results indicate that the generated photo-voltage is proportional to the intensity of the illumination light, and the photo-voltage measured under different wavelengths correspond to the absorption spectrum of bR.