DEVELOPING DEVICE, AND PROCESS CARTRIDGE AND IMAGE FORMING DEVICE EQUIPPED THEREWITH

PROBLEM TO BE SOLVED: To provide a developing device capable of preventing the lowering of image quality from being caused by the deterioration of developer, the lowering of the image quality from being caused by the solidification of toner and the rotation of a developer stirring and carrying member from being hindered by restraining temperature rise at the end of the developing device in the rotary axial direction of the developer stirring and carrying member even in the midst of long-time consecutive image forming while realizing the reduction of cost and the simplification of the constitution of the device, and to provide a process cartridge and an image forming device equipped with the developing device. SOLUTION: A vent hole 33 making space between a bearing 32a and a magnet 31 in an axial direction communicate with the outside of the developing device is formed so as to radiate heat at both ends of a 1st screw 2a in the axial direction to the outside of the developing device.