The present invention relates to a method of producing copper nanoparticles, in particular to, a method of producing copper nanoparticles, including: preparing a first solution including a polar solvent, a dispersing agent and one or more reducing agents selected from the group consisting of sodium hypophosphates(NaH2PO2), hydrazine(N2H4), hydrochloride and sodium borohydride(NaBH4) and heating the solution; preparing a second solution including a polar solvent and a copper precursor and heating the solution; and injecting the heated second solution into the heated first solution at a time and mixing each other. According to the present invention, copper nanoparticles which are fine and uniform can be produced simply, and thus the method is useful in mass production of copper nanoparticles.