Electrolyzed water obtained by electrolyzation of tap water was investigated as a means of controlling the solubility of steamed rice. The basic water obtained from the cathode side decelerated the solubility of steamed rice. On the other hand, acidic water obtained from the anode side accelerated the solubility of steamed rice. It was confirmed that the effect caused the elecrtolyzed water was greatly influenced by the rice koji. Hence the extracted enzymes were examined. It was thought that in the case of basic water, the cause of the repression of steamed rice solubility was the decrease in the quantity of the acid protease extracted. In the acidic water case, it was suggested that the cause of the acceleration of steamed rice solubility was the increase in the quantity of extracted a amylase and acidic protease. In addition, the effect of electrolyzed water on acid protease activity was investigated. The results showed that acid protease was activated by acidic water and was inactivated by basic water.