Abstract: The present invention is directed to the provision of a developing apparatus that can prevent copy quality degradation. The invention comprises a developing sleeve for supplying toner to a photoconductor drum surface, and a brush-thickness control member disposed in close proximity to the developing sleeve. The invention further includes limiting device, disposed adjacent to and upstream of the brush-thickness control member with reference to the rotating direction of the developing sleeve, for limiting the advance of the tip of an erected developer brush by pushing the tip toward the upstream side. Furthermore, there is provided, substantially below the limiting device, a guide end portion for receiving the whole or part of the developer limited by the limiting device and separated from the erected developer brush and for guiding the received developer in a direction moving away from the developing sleeve.