Abstract: Highly-pure water is stored into a storage tank 46 by reducing an impurity-ion content to not greater than a specified rate by removing impurity ions via a device 43, for manufacturing pure water, containing ion-exchange resin, and by reducing a dissolved-oxygen content to not greater than a specified rate by heating-deaerating with a heater 44 and reducing the pressure during storage in the storage tank 46. Highly-pure water to be stored is injected from a gun 10 into a vessel body 1 while detecting a flow-rate via a mass-flow meter 53. Therefore, a highly-accurate amount of water, with high purity, can be filled into the vessel body 1.