Electrolyzed water was applied to control microorganisms during the soybean soaking process of packed tofu processing. Acidic electrolyzed water (pH 2.1; oxidation reduction potential, 1185; 100 ppm of available chlorine) and alkaline electrolyzed water (pH 11.7; oxidation reduction, potential. -120) were prepared by electrolysis of 0.075% sodium chloride solution. Mixed electrolyzed water (pH 6.5; oxidation reduction potential, 891; 50 ppm of available chlorine) was prepared by mixing acidic and alkaline electrolyzed water to adjust pH to 6.5. Sterilization effects during soybean soaking and quality of soymilk and tofu produced from soybeans soaked in the three types of electrolyzed water were analyzed. Results show that microorganisms in soybeans can be effectively sterilized by using acidic electrolyzed water or mixed electrolyzed water as soybean soaking water, although the available chlorine concentration, which can be considered to reflect the electrolyzed water condition, decreased time dependently. We conclude that mixed electrolyzed water is the best disinfectant among the three types of electrolyzed water, due to weakly acidic pH, stability, and lack of damage to soymilk and tofu.