Ultrahigh purity copper having a residual resistance ratio of 38,000 or greater and a purity of 8N or higher (excluding gas components), and in particular ultrahigh purity copper wherein the respective elements of O, C, N, H, S and P as gas components are 1 ppm or less. Further provided is a method of subjecting copper to high purification. An anode and a cathode are partitioned with an anion exchange membrane, an anolyte is intermittently or continuously extracted and introduced into an active carbon treatment vessel, a chlorine-containing material is added to the active carbon treatment vessel so as to precipitate impurities as chloride, active carbon is subsequently poured in and agitated so as to adsorb the precipitated impurities, the adsorbed impurities are removed by filtration, and the obtained high purity copper electrolytic solution is intermittently or continuously introduced into the cathode side and electrolyzed.