According to the present invention, regarding a membrane 1 of which one surface 1b is arranged on a liquid side and the other surface 1a is arranged on a gas side, the surface 1b of the membrane on the liquid side is brought into contact with a disinfecting agent 2, while the other surface 1a of the membrane on the gas side is brought into contact with a gas 3, and a high level of sterilization is achieved within the membrane by causing the pressure on the gas side to be lower than that on the liquid side. Further, a differential pressure-forming mechanism configured so as to be able to implement this sterilization method is provided to a gas-dissolution liquid producing apparatus.
