Abstract: The present invention has an object to provide a highly stable cleaning solution that generates a high concentration of hypochlorous acid during cleaning, and has sterilizing and washing out activity on bacteria and viruses. As means for achieving this object, a cleaning solution has been developed which is an aqueous solution containing hypochlorous acid and hypochlorite ions produced using a diaphragm-free electrolysis process. The effective residual chlorine concentration thereof and the hydrogen ion concentration exponent thereof are adjusted to a value from 500 ppm to 2000 ppm and to a value from pH 8.5 to pH 9.5, respectively. Thus, the cleaning solution remains stable for a prolonged period of time, and exhibits high sterilizing and wash-out activity during use.