To provide a method for purifying carbon nanotubes by which metal impurities such as a metal catalyst can be efficiently and easily removed from the carbon nanotubes containing the metal impurities.

The method for purifying carbon nanotubes includes a first process, a second process, and a third process. The first process comprises subjecting the carbon nanotubes containing the metal impurities to a cutting treatment in a solution thereby obtaining a treating solution containing the metal impurities and crushed carbon nanotubes. The second process comprises subjecting the metal impurities and the crushed carbon nanotubes to electrophoresis by applying a voltage between electrodes in the treating solution. The third process comprises recovering the carbon nanotubes free from metal impurities accumulated on one electrode.