To provide a method and an apparatus for producing ozonated water by utilizing surplus ozone.

The method for producing ozonated water includes an ozone generation means, fluid feed means, ozone dissolution means for dissolving ozone in the fed fluid, and gas/liquid separation means which separate ozone remaining undissolved in the ozone dissolution means, wherein the ozone dissolution means and the gas/liquid separation means constitute one unit on the same line, at least two such units are arranged on their respective lines parallelly branched from the fluid feed means, and the ozone separated in the gas/liquid separation means in one unit is sent to the ozone dissolution means in the other unit.