PURPOSE: To impart suitability to oil-less fixing by which a releasing liq. such as silicone oil is not supplied to the surface of a fixing roll by incorporating an electric charge controlling material coated with a releasing material into the surfaces of particles based on a thermoplastic resin and a colorant.

CONSTITUTION: Particles based on a thermoplastic resin and a colorant are produced by kneading and pulverization, an electric charge controlling material is coated with a releasing material and the particles are mixed with the coated electric charge controlling material. Fine powder coated with the releasing material is fixed on the surfaces of the particles by applying mechanical shocks to the resulting mixture to form layers contg. the electric charge controlling material coated with the releasing material on the surfaces of the particles. Pulverized particles of only the thermoplastic resin may be used.