The present disclosure provides a method for producing carbon nanoparticles at low cost and with good efficiency. According to the disclosure of the present description, a voltage is applied between a graphite positive electrode and a negative electrode in an aqueous medium to generate arc discharge in a gap. An inert gas is introduced into the gap from a cylinder bottle at a predetermined flow rate. In this manner, carbon nanoparticles can be produced from carbon steam that is generated in the gap as a result of the arc discharge.