A method of forming nitrogen-doped single-walled nanotubes including: forming a catalyst metal layer on a substrate; loading a substrate having the catalyst metal layer into a reaction chamber; forming an H2O or other plasma atmosphere in a reaction chamber; and forming the nitrogen-doped nanotubes on the catalyst metal layer by supplying a carbon and a nitrogen into a reaction chamber where a chemical reaction therebetween is generated in the H2O or other plasma atmosphere.