We report recent progress on sputter-growth of Nb-doped anatase TiO 2 (TNO) polycrystalline films, being a promising ITO-alternative transparent conductor. In order to achieve low resistivity (ρ) in TNO, it is necessary to grow anatase phase under reducing atmospheres. However, growth of TNO polycrystalline films on glass under such conditions tends to stabilize rutile phase with higher resistivity. To overcame this difficulty, we have developed a bi-layer technique using a TNO self seed-layer, which prevents the formation of the rutile phase even under reducing growth conditions. As a result, we succeeded in directly fabricating TNO polycrystalline films with ρ of ∼1×103 Ω cm and visible transmittance of 60 ∼ 80%, although we still need to further improve these properties towards practical applications. By comparing dc transport properties with optically deduced ones, we discuss material parameters that limit carrier transport in presently obtained TNO polycrystalline films.