A method for preparing carbon nanotubes including attaching a catalyst consisting of a compound in which a transition metal element of Group 8, 9 or 10 is coordinated to a nitrogen-containing dendrimer compound having at least one nitrogen atom, to which a metal element may be coordinated, on a surface of a substrate, and thermally decomposing a carbon compound in the vicinity of the substrate while supplying the carbon compound on the surface of the substrate to which the catalyst is attached. The catalyst for producing the carbon nanotubes is a compound in which a transition metal element of Group 8, 9 or 10 is coordinated to a nitrogen-containing dendrimer compound having at least one nitrogen atom to which a metal element may be coordinated.