A graphite cathode and a graphite anode are placed opposite each other through an insulating plate having a notch. A voltage is applied between both of the electrodes to generate arc discharge at the notch of the insulating plate. A given area of the graphite anode is evaporated from an electrode point of the arc discharge, and simultaneously an arc jet is generated from the notch. Thereby, a carbon nanoparticle comprising soot of carbon nanomaterial containing carbon nanohorn is generated. The soot is deposited on a recovering plate for recovery.