We have demonstrated that the normal‐state resistivity of sufficiently thick Y1Ba2Cu3O7−&dgr;thin films can be fitted very well by the Bloch–Gruneisen equation. As the film thickness decreases, the localization effect becomes predominant presuming the manifestation of surface defects and vacancies over the bulk region. The evaluated Debye temperatures span over a range which is consistent with experimental values. Below some critical thicknesses, the transport behavior in thin Y1Ba2Cu3O7−&dgr;films deviates from the Boltzmann conductivity and the temperature coefficient of the electric resistivity becomes negative, which can be explained by adopting quantum corrections for localization and interaction effects. The origin of nonmetallic behavior can be understood quantitatively in terms of the competition between the quantum corrections and the conventional Boltzmann conductivity. In these ultrathin superconducting films, the elastic mean‐free path arising from defect and heavy impurity scattering is very short and much smaller than the inelastic mean‐free path, even at room temperature.