Intercalation of methylene blue into K4Nb6O17 single crystals was investigated for the construction of hybrid materials with three-dimensional anisotropy. By the reaction of K4Nb6O17 with a methylene blue aqueous solution in the presence of propylamine, methylene blue/K4Nb6O17 intercalation compounds were obtained. The basal spacing increased to 3.0 run, and the macroscopic thickness of the crystal also increased. The regularity in the ac plane did not change by the reaction as evidenced by the in-plane X-ray diffraction measurements. Polarized absorption spectra showed a dichroism showing that the methylene blue/K4Nb6O17 intercalation compounds possess three-dimensionally confined nanostructures.