A method is provided, comprising: preparing a hydrogen generating agent (14) that reacts with water to generate hydrogen gas, a first container (11) that encloses a liquid (16) applicable to a living organism and has hydrogen gas permeability, and a second container (12) that has hydrogen gas permeability equal to or lower than the hydrogen permeability of the first container； storing the first container and the hydrogen generating agent in the second container and sealing the second container with no water except moisture in air； maintaining the second container storing the first container and the hydrogen generating agent in a frozen state from when the second container is sealed until when the liquid is used； upon use of the liquid, placing the second container storing the first container and the hydrogen generating agent in an unfreezing atmosphere so that the hydrogen generating agent reacts with water in the second container to generate hydrogen gas in the second container, the water in the second container including water vapor resulting from vaporization of water contained in the liquid stored in the first container and permeation of the water vapor through the first container into the second container and/or the moisture in air in the second container； and allowing the hydrogen gas generated in the second container to pass through the first container so that hydrogen molecules are contained in the liquid stored in the first container.
