DEVELOPING DEVICE

PROBLEM TO BE SOLVED: To provide the developing device of a copying machine, a printer, a facsimile equipment or the like constituted so that a clear image is formed without the splash of developer and stain. SOLUTION: The width in the shaft direction of a regulation member 8 regulating the quantity of developer to be a prescribed value is set to be narrower than the width of a developer carrier 6 in the shaft direction and wider than the width of the developing chamber 4 of a developing case 1 storing the developer 2. Besides, a first seal member 15a is arranged at a gap between the carrier 6 on the outside of the chamber 4 and the case 1 and a second seal member 15b is arranged at a gap between the carrier 6 on the outside of the regulation member 8 and the case 1. By making the contact angle of the regulation member 8 regulating the layer thickness of the developer by bringing the vicinity of the edge thereof into press-contact with the carrier 6 smaller at the vicinity parts of both ends of the regulation member 8 in comparison with the central part thereof, toner is surely prevented from being leaked from both end parts of the regulation member 8.