Aluminum electrode thin films (33, 53, 90 nm thick) with various widths were simultaneously deposited on lithium tantalate by electron beam evaporation. The width dependence of resistivities of the thin films were observed by Van der Pauw method and the structure of the films was investigated by cross-sectional TEM (XTEM). The result shows that the resistivities depend on the electrode width in the narrow width range, less than 1 mm, and that the resistivities are expressed as the sum of size-independent part, the thickness-dependent part, and the width-dependent part. The resistivity formulas are introduced for latter parts. The result of the resistivity measurements was discussed in comparison with the structural aspects by XTEM observations.