The detergency of electrolysis water in laundering was studied. First, contact angle with cellophane and PET films was measured. In both films, the contact angle decreased with increasies in the pH of electrolysis water. Electrolysis water of pH 11 was absorbed nearly completely by cellophane in 30 minutes. In addition, various kinds of water were examined for water absorption by fabrics. The absorption rate of electrolysis water of pH 11 was more rapid than other kinds of water. It was found to possess very high permeability into the fabrics.Artificial soiled fabrics were laundered in various kinds of water. The result revealed that electrolysis water of pH 11 showed high detergent efficiency for such hydrophilic materials such as cotton, silk, and wool that were artificial soiled fabrics. Furthermore, when sodium dodecylbenzenesulfonate, a surfactant, was added to launder them, detergent efficiency was further improved by the addition of sodium dodecylbenzenesulfonate. Surfactant decomposition by active oxygen formed was not inferred to take place much in laundering in electrolysis water from this finding. In addition, a test was performed to examine soil redeposition in cotton and polyester fabrics with water-soluble and oil-soluble soil. It was found difficult to redeposit soil in them when laundering them in electrolysis water of pH 11. However, although the cotton and polyester fabrics were not found much damaged after laundering, the wool fabric was observed to be damaged when electrolysis water (pH = 11) was used. The extent of damage was about the same as that found when a sodium hydroxide solution (pH = 11) was used instead.