PURPOSE: To improve the sharpness of an image by supplying a magnetic toner to the surface of a magnetic recording medium and using the toner which generates potential when only the permanent magnet member provided in said medium is rotated for prescribed time and of which the potential is a specific value or below.

CONSTITUTION: A non-magnetic sleeve provided internally a permanent magnet member having plural magnetic poles is disposed to face a magnetic recording medium holding a magnetic latent image. A toner consisting essentially of a resin and magnetic powder is then supplied onto said sleeve. The magnetic toner is conveyed to the spacing where the magnetic recording medium and the nonmagnetic sleeve faces each other by the relative rotation of the permanent magnet member and the nonmagnetic sleeve by which the magnetic toner is stuck to the magnetic latent image and the image is thus developed. The magnetic toner of the layer thinner than the above-described spacing is supplied onto the nonmagnetic sleeve while the magnetic latent image is not perfected yet on the surface of the magnetic recording medium. The magnetic toner which generates potential when only the above-described permanent magnet member is rotated for prescribed time and of which the potential is within the range of ≤15V absolute value is used. The image having no photographic fog is obtd. by using the above-mentioned toner in the developing region including a developing gap D.