A method for manufacturing carbon nanotubes of the present invention includes the steps of: preparing at least one metal selected from a group consisting of iron, cobalt and nickel and an organic compound: and forming carbon nanotubes by using the organic compound as a carbon source, wherein the metal and the organic compound are put into a heating vessel having a substance capable of converting electromagnetic energy into heat, and the organic compound is brought into contact with the metal in a state where the inside of the heating vessel is heated at a temperature of 600° C. to 900° C. by applying the electromagnetic energy to the heating vessel so as to form the carbon nanotubes.