The present invention provides an ozonization apparatus which is not only capable of dissolving ozone in material water with high efficiency and speedily but also enables the easy and proper control of the dissolved ozone concentration of ozone water. The present invention relates to an ozonization apparatus comprising

• an ozone gas-permeable membrane disposed to isolate material water and ozone gas from each other and allow said ozone gas to be dissolved in said material water by permeation, said ozone gas-permeable membrane being a nonporous hollow tube which is selectively gas-permeable and liquid-impermeable.