PURPOSE: To prevent a developing agent from adhering the outer wall of a developing agent storage container and staining the developing agent storage container, or prevent the developing agent from flying around and damaging the surrounding environment, when a powdery developing agent is filled in a developing agent storage container.

CONSTITUTION: When a developing agent 1 is filled in a developing agent storage container 2, a developing agent storage tank such as a hopper 11, etc., in which the developing agent 1 is stored, and a feeding means which feeds the developing agent 1 stored in the developing agent storage tank from a feeding port 18e to the developing agent storage container 2 through a mouth part 2a of the developing agent storage container 2 are provided. Also, a carrying means which carries the developing agent storage container 2 to a feeding position at which the developing agent 1 is fed from the feeding means, and a collecting means which collects the developing agent 1, which drops from the feeding port 18e, by jetting air to the vicinity of the feeding position at which the developing agent 1 is fed to the developing agent storage container 2 from the feeding means are provided.