Disclosed herein is a method of forming a guanidine group on carbon nanotubes to improve the dispersibility of carbon nanotubes, a method of attaching carbon nanotubes having guanidine groups to a substrate, and carbon nanotubes and a substrate manufactured by the above methods. The method of forming the guanidine group on the carbon nanotubes includes forming a carboxyl group on the carbon nanotubes, and forming the guanidine group on the carboxyl group of the carbon nanotubes. In addition, the method of attaching the carbon nanotubes having guanidine groups to the substrate includes coating a substrate with a polymer having crown ether attached thereto, drying the polymer layer having crown ether attached thereto formed on the substrate to be semi-dried, and coating the semi-dried polymer layer with a solution including carbon nanotubes having guanidine groups dispersed therein. The carbon nanotubes having guanidine groups, which are manufactured by the method of the current invention, are hydrogen bonded with the solvent molecule capable of reacting with the guanidine group to form the hydrogen bond, and thus, are uniformly dispersed in the solvent. Further, by using the properties of the guanidine group capable of being selectively combined with crown ether, the carbon nanotubes having guanidine groups are aligned perpendicularly to the substrate at regular intervals thereon.