A developing device is disclosed which includes a fixed magnet roller 25 having a plurality of magnetic poles, a development roller 27 having a development sleeve 26 that is supported axially with the ability to rotate freely, and a magnetic sealing member 29 arranged at the end of the longitudinal direction X of the development sleeve 26. Further, the length of each of the plurality of magnetic poles not facing the magnetic sealing member 29 (in other words, the development pole SI, lead-in pole N1, and blade pole N3) of the fixed magnet roller 25 are shorter than the length of each of the plurality of magnetic poles facing the magnetic sealing member 29. Accordingly, the magnetic toner retained on the peripheral surface of the development sleeve 26 is guided to the development area side in the longitudinal direction X of the development sleeve 26.