La 1−x Ba x MnO 3 thin films (0.05≤x≤0.2) with a tensile strain from substrate exhibit unusual film thickness dependence on the Curie temperature T C . The T C was found to increase up to room temperature with decreasing film thickness. In this study, the origin of the T C enhancement is examined by performing Hall measurements. The carrier densities of various thick films were found to be almost constant value (∼6×10 20 cm −3 ) at 10K, whereas Hall mobility drastically increased, from 5cm 2 /Vs for 729-nm thick film to 50cm 2 /Vs for 24-nm thick film. These results indicate that the T C enhancement is induced by increase of carrier transfer due to lattice deformation of Mn–O–Mn networks.