Titanium oxide nanowires with a feature width as narrow as ∼20 nm were induced on a titanium surface by using femtosecond laser pulses at 400 nm. An evolution of the surface structure from a high spatial frequency laser-induced periodic structure parallel to the laser polarization to a low spatial frequency one perpendicular to the laser polarization was observed with increasing irradiation pulse number. The formation of the titanium oxide nanowires was confirmed by the energy dispersive spectroscopy measurements and the evolution of the surface structure was successfully interpreted by using the efficacy factor theory.