This paper describes the elucidation about the influence of electrolyzed oxidizing water (It abbreviates as EO water) on copper nickel alloy for lead frame. First, the etching characteristics of EO water against the surface of copper nickel alloy for lead frame was clarified using chemicals for comparative immersion experiments. The comparative study showed that as for the etching efficiency on copper iron alloy, Na₂SO₄ EO water was superior to H₂SO₄ solution, and NaCl EO water was superior to HCl solution. Also, EO water has the selective etching tendency to Cu element in copper nickel alloy for lead frame like chemicals. As for the relationship between immersion time and etching depth, Na₂SO₄ EO water is same as NaCl EO water, and become proportional connection. Next, by the observation using SEM image, the influence of EO water on the surface shape of copper nickel alloy for lead frame was clarified. The results indicated that Na₂SO₄ EO water did not have a big influence on the surface shape. However, when using NaCl EO water, the dimples occurs, and when using H₂SO₄ solution, projection occurs in the surface. Lastly, as for the test piece after heating processing, it did the surface oxidation layer removal experiment by the immersion. The results show that EO water can remove the surface oxidation layer like chemicals, and Na₂SO₄ EO water remove the surface oxidation layer more efficiently than NaCl EO water