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.