PURPOSE: To improve the transfer and the static charge characteristic of a toner and to eliminate failure caused by covering the toner particle with a dried additive having very small diameter by forming the film of fine particles which disperse in aq. dispersion, stick strongly to the toner particle and have specific average particle diameter on the surface of the toner particle of a thermoplastic resin.

CONSTITUTION: The toner particle surface of a thermal fixing composition is uniformly covered with the fine particle and the fine particle is applied by using the aq. dispersion. The fine particle can be either of an inorganic material or an organic polymer. The average particle diameter of the fine particle is defined as 0.01-0.2μm. The fine particle is applied on the starting toner particle by mixing the aq. dispersion with the starting toner particle by strong mechanical agitation. Next, the toner particle covered with the slurry is dried by being heated in an atmospheric pressure or reducing pressure while continuing the mechanical agitation of the mixture.