This invention relates to a method to induce growth of carbon nanotubes using a liquid phased-hydrocarbon based material under a critical range of equilibrating between liquid and gas phases, thereby easily manipulating a required carbon source. This invention also relates to a method to facilitate easy generation of a carbon backbone of the carbon nanotube because the reaction is performed in the presence of a metal nanoparticle or a metal compound capable of spontaneously generating a seed catalyst which stimulates the growth of carbon nanotubes as well as secures safety enough for the industrial application by using a mild reaction condition within the critical range. Accordingly, this invention can produce the carbon nanotube with high transition efficiency under a mild condition with a relatively lower temperature and pressure than those in conventional gas phased-methods without using a costly equipment, thereby cost-effectively producing the carbon nanotube in large quantities.