Photo-N doping for Nb-O system oxide nanosheets such as Nb6O17, TINbO5, and Ca2Nb3O10 was succeeded in by treatment under mild conditions, where their H-restacked forms containing tetrabuthylammonium (TBA) ion were illuminated by UV light at room temperature. A relatively strong absorption in visible tight region (400 similar to 600 nm) was observed for the N-doped samples because of formation of p-band or valence band hybridization of N in the Nb-O bandgap. The N doping proceeded only under TBA presence in water without O-2, and Pt loading promoted this doping reaction. It is proposed as a mechanism from the results of the doping for the Ti-O and Nb-O nanosheet mixed samples, that the Nb-O nanosheet acts as a photocatalyst for the N-doping reaction. This is the first report of N doping to oxide nanosheets.