PURPOSE: To form stably high density and clear visible images for a long period without causing fog by using powder of a specified particle size obtd. by dispersing fine powder of a magnetic body in a cross-linked polymer as a resin binder.

CONSTITUTION: Powder or 10W50μm average particle size obtd. by dispersing fine powder of a magnetic body in a resin binder prepd. by cross-linking a cross- linkable polymer with a cross-linking agent is used as a carrier. Since the resin binder has a three-dimensional structure, the carrier has superior durability. The triboelectric chargeability of the carrier can be made positive or negative according to the kind of the polymer, and when the positively or negatively chargeable carrier is used, a toner is charged stably and sufficiently to the reverse polarity for a long period and can be stuck well to a latent image. It is not necessary to add a charge controller, and the surface of the carrier is kept clean. The permitted limit of the concn. of the toner in a two-component developer is extended, facilitating the supply of the toner. Since the head of the brush of a developer layer is made fine and soft, a high density and clear image free from fog as well as a uniform image of high quality can be formed.