The photoelectrochemical properties of the polycrystalline doped with 3d transition metals (Cr, Mn, V, Cu, Ni, and Zn) have been investigated. The electrodes doped with Cr, Mn, V, and Cu show the visible light photoresponses. It is concluded that the visible light photoresponse is based on the impurity band formed near the π* conduction band of the in energy position, in analogy with the Co‐doped electrode reported previously. The cathodic photocurrent of the reduction was also observed for the doped and undoped electrodes. From the good agreement of the spectral dependences of the anodic and cathodic photocurrents, it is judged that both type photocurrents are brought about by the same photoexcitation process. The observed large cathodic photocurrents for the electrodes that give the visible light photoresponse are attributable to the d‐orbitals of the doped metal as the active site, by which the impurity band is formed in the bulk. A mechanism for the photosynthesis is also suggested from the simultaneous appearance of the photo‐oxidation and photoreduction currents on an electrode.