To obtain excellent quietness even in a shaft integrated type magnet roller by improving the roundness of a shaft part up to a level at which a noise is not generated.

This developing roller is provided with a cylindrical sleeve 2 freely rotatably disposed and the magnet roller 1 rotatably disposed inside the sleeve 2. In the magnet roller 1 constitute in such a manner that a magnet body 11 and the shaft 12 projected from both or one end of the magnet body 11 are integrally formed out of a bond magnet composition obtained by dispersing magnetic powder in resin binder, the roundness of the shaft 12 is set ≤30 μm. In such a case, a developer is carried on the outer periphery of the sleeve 2 by the magnetic characteristic of the roller 1, to form a thin film of the developer. In this state, an approach to an image forming body is made and the developer is made to soar to the surface of the image forming body, to be supplied by the magnetic characteristic of the roller 1, so that a visible image can be formed on the surface of the image forming body.