Self-organization of a two-dimensional array of nanopores, which was formed by anodic oxidation of aluminum, was investigated quantitatively using scanning electron microscopy (SEM) images and their fast Fourier transformation analysis. The highly ordered array of nanopores with diameters of ~60 nm was obtained by two-step anodization at an anodizing voltage of 40 V for an anodizing time of 36 h in a 0.3 M oxalic acid. A two-dimensional ordered array of ferroelectric PbTiO3 nanotubes was successfully fabricated by a spin coating of sol-gel solution into porous anodic alumina template. SEM and transmission electron microscopy images show that the nanotubes have a relatively constant wall thickness of ~15 nm with an outer diameter of ~60 nm. The present method has a high efficiency to fabricate an ordered nanotube array of a variety of functional metal oxide materials in a large area.