PURPOSE: To prevent blocking and to obtain efficient developing property by carrying magnetic toner containing iron oxide of specific quantity or more and having volume resistance in a specific range at a specific moving 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 adered 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 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 to 60wt% or more. However, if the content exceeds 80wt%, fixing property is extremely deteriorated. Considering the developing property, the volume resistance of the magnetic toner 9 is set up to 108W1012Ω.cm and it is preferable to set up the grain size of the toner to 5W50μm.