| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device and an image forming device by which the deterioration of a conductive resin covering layer on a developer carrier surface due to repeated copying and endurance is hardly caused, and which have excellent durability even under a different environmental condition and also by which an image high in density and quality without causing any image defect is stably obtained even in the case of using spherical toner small in grain size and having low-temperature fixability. SOLUTION: Negative electrostatic chargeable developer having toner 4 whose ratio of a grain having the diameter of equivalent circle of >=0.60 μm to <1.0 μm is <5.0% in number-size distribution based on the diameter of equipvalent circle measured by a flow-type grain image analyzing device and having inorganic fine powder is used, and also a developer carrier 8 having a conductive resin covering layer 7 containing at least a binder resin for a covering layer, a conductive fine powder dispersed in the binding resin for the covering layer and a nitrogen-containing heterocyclic compound is used. |
