A flexible tank has a volume-variable chamber formed so as to be sectioned by a flexible tube that is expanded or contracted in accordance with the amount of the contained chemical liquid, and adaptor parts attached to the flexible tube. A primary-side port open to the volume-variable chamber is open into one of the adaptor parts, and a secondary-side port open to the volume-variable chamber is open into the other adaptor part. The contact between the chemical liquid and air in the volume-variable chamber is suppressed to minimum level, thereby containing the chemical liquid without deteriorating the cleanliness of the chemical liquid, and improving discharge accuracy of the chemical liquid.