The present invention provides an additive for high-purity copper electrolytic refining and a method of producing high-purity copper using the additive. The additive of the present invention for high-purity copper electrolytic refining can be added to a copper electrolyte in electrolytic refining for producing high-purity copper. The additive includes a main agent formed of a non-ionic surfactant which has a hydrophobic group containing an aromatic ring and a hydrophilic group containing a polyoxyalkylene group, and a stress relaxation agent formed of a polyvinyl alcohol or a derivative thereof.