An apparatus for manufacturing a carbon nanotube includes: at least two electrodes whose tips oppose to each other; a power supply which applies a voltage between the electrodes so as to generate discharge plasma in a discharge area between the electrodes; a plurality of magnets which generates at least one of a magnetic field having lines of magnetic force in multiple directions or a magnetic field having a component in parallel with the direction of a discharge current in the generation area of the discharge plasma; and a magnet cooling unit which cools the magnets.