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Highly aligned and isolated single-walled carbon nanotubes (SWNTs) were grown on the R-face (11¯02) and A-face (112¯0) surfaces of sapphire (Al₂O₃) substrates by catalytic chemical vapor deposition. On the basis of the electron backscatter diffraction (EBSD) analysis, we have found that the SWNTs are aligned along the specific crystalline directions corresponding to the anisotropic pseudo-one-dimensional array of Al atoms on these surfaces. This suggests that the Al array guides the SWNT growth due to the strong interaction between the Al atoms and nanotubes. On the other hand, a random orientation has been observed for the SWNTs grown on the C-face (0001) substrate, reflecting the isotropic arrangement of Al atoms. These findings indicate that the strong interaction between the SWNTs and substrate surface is applicable for patterning or integrating SWNTs in nanoelectronics applications.