The structural change on the molecular scale of anatase-type TiO(2) during hydrothermal treatment was investigated in detail by various analytic techniques such as X-ray absorption fine structure and transmission electron microscopy in order to clarify the formation mechanisms of titanate-based nanotubes. It revealed that the nanosheet-like products composed of highly distorted TiO(6) octahedra were generated by hydrothermal treatment of anatase-type TiO(2), and then the anatase-like structures are partially built up with the formative nanotubes by scrolling up these nanosheet-like products and nanosheets.