Using a solid-state-reaction method, La-doped AgNbO(3) samples of Ag(1-x)La(x)NbO(3) were synthesized and their photocatalytic activities were evaluated from gaseous 2-propanol decomposition under visible light irradiation. The photocatalytic activity and the surface area were increased by La doping, but the crystal structure and light absorption property did not change. The photocatalytic activity of Ag(1-x)La(x)NbO(3) was significantly improved over that of AgNbO(3). The Ag(0.88)La(0.12)NbO(3) sample displayed the highest photocatalytic activity: it was more than 12-fold higher than that of AgNbO(3).