This paper describes the influence of NaCl EO water (electrolyzed oxidizing water) on the surface of Permalloy 78. First, the etching efficiency of NaCl EO water on the surface of Permalloy 78 was made clear by comparing it with the etching efficiency of soaking in HCl solution. The comparative study showed that as for the etching efficiency on the surface of Permalloy 78, NaCl EO water was superior to HCl solution. Also, NaCl EO water can process an etching equally to each composition elements of Permalloy 78 compared with HCl solution. Next, by analyzing the surface, the influence which NaCl EO water exerts on the chemical composition in the surface of Permalloy 78 was made clear. The results showed that NaCl EO water does not have any bad influences on the chemical composition of Permalloy 78. By this study, we got the suggestion that NaCl EO water can be applied to the surface processing of Permalloy 78.