PURPOSE: To prevent the change of properties and the condensation of a reagent by adding a substance into a container of the reagent which shuts the liquid surface of the reagent from the outside air.

CONSTITUTION: At a production site of a reagent, a reagent 2a is filled in a reagent vessel 1a and a seal 6a resistive to medicines is tightly held in touch with the vessel 1a by means of a lid 5a, which is then packaged and preserved or brought in the market. At the using time, the lid of a vessel 1b is removed, so that a room 3b is opened to the air. In order to avoid this, a shutting agent 4a taken in a dispenser instrument 7g is added to the reagent 2b, so that the reagent is shut by a shutting agent 4c. Since the reagent 2b and room 3b are shut, the change of properties of the reagent 2b due to the oxygen and carbon dioxide in the air and the condensation of the reagent 2b as a result of the evaporation of moisture are solved. When the reagent is to be fed to an automatic analyzer, a reagent tube 8a connected to a dispenser device is inserted together with a weight into a reagent 2c. The reagent 2c is automatically consumed and consequently, the shutting agent 4c becomes lower. Nevertheless, the reagent 2c and a room 3c are still shut from the air. The property change and condensation of the reagent 2c are accordingly not given rise to.