DEVELOPING DEVICE

PROBLEM TO BE SOLVED: To enhance reliability of a developing device 122 using a developer T in which an additive is mixed in one-component magnetic toner. SOLUTION: An additive recovering box 20 for recovering an additive by making it fall by gravity is attached to a developing container 122a so as to be communicated with the developing container 122a, the additive being accumulated one-sidedly in the developing container 122a with the consumption of the one-component magnetic toner comprising the developer T. In the communicative part between the additive recovering box 20 and the developing container 122a, a filter member 20b is disposed which has a large number of meshes through which the particles of the additive are passed but not those of the one-component magnetic toner, so that image forming operation is maintained in good condition. COPYRIGHT: (C)2004,JPO