The DC arc plasma jet method was newly developed for the mass-production of single-wall carbon nanotubes (SWNTs). The quantity of cathode deposit was efficiently reduced by this method, and the production rate of cotton-like soot including SWNTs was significantly higher than that by conventional DC arc discharge evaporation. Investigation by using scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy indicated that more than 50% of the cotton-like soot was the fibrous bundles of SWNTs with diameters of 1.34-1.53 nm.