This paper describes the influence of Na2SO4 electrolyzed oxidizing water on the surface of pure nickel. First, the etching characteristic of Na2SO4 electrolyzed oxidizing water on the surface of pure nickel was made clear by the comparative immersion experiments with NaCl electrolyzed oxidizing water and H2SO4 solution. The results show that as for the etching effects on pure nickel, Na2SO4 electrolyzed oxidizing water is same as the NaCl electrolyzed oxidizing water and becomes stronger than H2SO4 solution. Next, we threw light on the influence of Na2SO4 electrolyzed oxidizing water on the surface shape of pure nickel, by the observation using the SEM and the AFM image. The results indicated that Na2SO4 electrolyzed oxidizing water did not have a big influence on the surface shape of pure nickel. Lastly, by analyzing the surface, we made it clear that Na2SO4 electrolyzed oxidizing water can remove the surface oxidation film of the pure nickel. Na2SO4 electrolyzed oxidizing water does not have chloride ion, unlike NaCl electrolyzed oxidizing water. Therefore, Na2SO4 electrolyzed oxidizing water is wide in the application scope, compared with NaCl electrolyzed oxidizing water.