The purpose of the present invention is to manufacture ozone-gas-dissolved water that has a high concentration of ozone gas in solution and which suppresses bubbling of oxygen gas in the place of use. Using the manufactured ozone-gas-dissolved water, electronic materials can be cleaned efficiently, avoiding problems with uneven cleaning and mechanical breakage caused by air bubbles. When the ozone-gas-dissolved water is manufactured by supplying a mixed gas of ozone gas and oxygen gas and deaerated water into an ozone dissolution unit and dissolving the mixed gas in the supplied water, the amount of mixed gas supplied to the ozone dissolution unit is controlled so that the total of the amount of oxygen gas dissolved in the supplied water, and the amount of oxygen gas in the mixed gas in a case where all of the ozone in the mixed gas has broken down into oxygen, is equal to or less than the saturation solubility of the oxygen gas, under the use conditions of the ozone-gas-dissolved water that has been obtained.