Carbon nanotubes (CNTs)/Ta3N5 nanocomposite is presented as a novel photocatalyst working under visible light irradiation. The results of Fourier transform infrared analyses and transmission electron microscopy indicate that a good interfacial combination has formed between CNTs and Ta3N5 nanoparticles. The CNTs/Ta3N5 nanocomposite shows strong absorption in the visible light range compared with pure Ta3N5 and has a bandgap energy of 2.01 eV. The photocatalytic experiments show that the nanocomposite has a higher photocatalytic activity than Ta3N5 nanoparticles.