PURPOSE: To prevent toner filming and deterioration of characteristics of toner, by coating the surface of each carrier particle with a polycondensation product resin of triazine A and bismaleimide.

CONSTITUTION: In an electrophotographic magnetic brush development process, 10W400pts.wt. carrier per 1pt.wt. toner is used. The surface of each particle of carrier, e.g., iron or ferrite, is coated with a nonadhesive heat-resistant resin to prevent the toner from melt-attaching to its surface and deteriorating charging characteristics. A BT resin is used for this resin, and it is obtained by polycondensing bismaleimide having formula II and triazine A having formulaIin which R1 and R2 are each H or 1W6C alkyl, and they may be same or different. This resin is dissolved in a solvent mixture of methyl ethyl ketone and the like, and sprayed on the surfaces of the carrier particles to form nonadhesive films.