DEVELOPING ROLLER, ITS MANUFACTURING METHOD, DEVELOPING DEVICE AND IMAGE FORMING DEVICE

PROBLEM TO BE SOLVED: To inexpensively provide a developing roller equipped with high magnetic characteristic and the high accuracy of a main pole part with simple constitution. SOLUTION: A magnetic roller disposed inside the sleeve 45 of the developing roller 41 is constituted by embedding three magnet blocks 48 at a part equivalent to the developing pole of a cylindrical magnet 47 on a holder 49 and bonded with nearly cylindrical magnet 47. Each magnet block 48 has a mutually different polarity to that of the adjacent one. By such constitution, the magnet block 48 is stuck by using the accurate holder only at a part where the high magnetic characteristic is required, and the developing roller having the characteristic required to obtain a good-quality image all over the density area is inexpensively realized with the simple constitution.