PURPOSE: To obtain a color developer having stabilized travelling property by using a specified resin-dispersed carrier as the carrier.

CONSTITUTION: This developer consists of at least a toner and carrier and is used for such an image forming device that has at least one of an electrifying device, exposing device and developing device under an endless-type image formation supporting body which is stretched between rotating rollers. The carrier is a resin-dispersed carrier produced by dispersing magnetic particles having 0.1-1.0μm number average primary particle size in a resin by 50-80wt.%. By preparing a developer in which the resin-dispersed carrier is used as the structural material, the specific gravity of the carrier is made small and shows good mixing property with the toner. Moreover, the developer can be easily carried to the upper part of the developing device. Or, by decreasing the difference of specific gravity between the toner and the carrier, the travelling property can be improved.