PURPOSE: To prevent blocking and to obtain efficient developing property by carrying magnetic toner of which content of iron oxide and volume resistance are specific values or more at a specific speed in the same direction as the moving direction of the surface of an image carrier.

CONSTITUTION: The magnetic toner 9 adsorbed to the surface of a non-magnetic sleeve 3 is carried in the arrow S direction by the relative rotation between the non-magnetic sleeve 3 and a parmanent magnetic member 6. The magnetic toner 9 passing through a doctor gap (d) is contacted with the surface of a photosensitive drum 1 near a developing gap D and adhered to the surface to form a toner image. Although it is necessary to speed up the carrying speed of the toner 9 as possible, it is proper to the set up the speed to 1.1 times or less the peripheral speed of the surface of the photosensitive drum 1. Efficient developing property is obtained by setting up the content of magnetic powder in the toner 9 to 60wt% or more. However, if the content of the magnetic powder exceeds 80wt%, fixing property is extremely deteriorated. Considering transferring property, the volume resistance of the magnetic toner 9 is set up to 1012Ω.cm or more and it is preferable to set up grain size to 5W50μm.