In this paper we discuss influence of Dilute NaCl-electrolyzed reducing water (ER water) on the surface of high carbon steel. First, the characteristics of dilute NaCl ER water and pure water for the comparative experiment was described. Next, the high carbon steel test pieces reviewed about the surface change such as the corrosion by the immersion processing to dilute NaCl ER water and pure water. The results show that pure water corrodes to the high carbon steel surface but dilute NaCl ER water doesn't corrode. Also, when doing immersion to dilute NaCl ER water, the alien substance which contains sodium mainly occurs. Moreover, when dry with drying oven after processing an immersion with dilute ER water, alien substance occurs much, but with the centrifuge, the occurrence of alien substance can reduce. The study indicates that dilute NaCl ER water can be applied to the surface treatment and washing of high carbon steel.