This paper describes the elucidation about the removal of surface oxidation layer of oxygen free copper after heating processing using NaCl-electrolyzed oxidizing water (It abbreviates as NaCl EO water). First, the etching characteristics of NaCl EO water against the surface of oxygen free copper was clarified using chemicals of HCl solution for comparative immersion experiments. The comparative study showed that as for the etching efficiency on oxygen free copper, NaCl EO water was superior to HCl solution, and the etching speed on the test pieces which has been processed in the heating compared with the material is high. As for the relationship between immersion time and etching speed, NaCl EO water is same as HCl solution, and become proportional connection. Next, by the observation using SEM image, the influence of EO water on the surface of oxygen free copper was clarified. The results indicated that when doing an immersion to NaCl EO water, the surface of the test pieces which has been processed in the heating becomes smooth but in the surface of the material, the etching appears remarkably. Lastly, as for the test pieces after heating processing, it did the surface oxidation layer removal experiment by the immersion. The results show that NaCl EO water can remove the surface oxidation layer like HCl solution.