In this paper we discuss the influence of electrolyzed oxidizing water (EO water) on the surface of Permalloy 45. First, we threw light on the etching efficiency of NaCl EO water and Na2SO4 EO water on the surface of Permalloy 45 bycomparing it with the etching efficiency of soaking in HCl solution and H2SO4 solution. The comparative study showed that as for the etching efficiency on Permalloy 45, NaCl EO water and Na2SO4 EO water was superior to HCl solution and H2SO4 solution. Also, EO water can process an etching equally to each composition elements of Permaooly 45 compared with chemicals. Next, by analyzing the surface, we made it clear that the influence which NaCl EO water and Na2SO4 EO water exerts on the chemical composition in the surface of Permalloy 45. The results showed that EO water does not have a bad influence on the chemical composition of Permalloy 45. By this study, we got the suggestion that EO water can be applied to the surface processing of Permalloy 45.