An embodiment of an apparatus for producing a sterilized water wherein each of an aqueous acid solution (21) and a chlorine-containing aqueous solution (31) is diluted with raw water (1) in a device (4) for inclusion, and then the resultant solutions are mixed in a mixer (5). The apparatus for producing a sterilized water can be used for satisfactorily exhibiting the sterilization ability of a chlorine-containing aqueous solution such as a sodium hypochlorite solution, a chlorine dioxide solution and a mixture thereof, while suppressing the generation of a chlorine gas, and for producing a desired sterilized water through suitably mixing water, an aqueous acid solution and a chlorine-containing aqueous solution at satisfactorily controlled concentrations.