PURPOSE: To produce a toner having superior environmental resistance, triboelectric chargeability and image characteristics by converting a gaseous fluorine-contg. monomer into plasma under specified conditions, bringing toner particles into contact with the resultant plasma atmosphere for a specified time and forming a plasma-polymerized film on the surface of each of the toner particles.

CONSTITUTION: A gaseous fluorine-contg. monomer is converted into plasma under the conditions of 5-150W high electric power and 2.66-266Pa pressure, toner particles are brought into contact with the resultant plasma atmosphere for 10sec to 30min and a plasma-polymerized film is formed on the surface of each of the toner particles. The toner particles consist of a bonding resin, a colorant and an electrostatic charge controlling agent or further contain other additives if necessary. A homogeneous polymerized film is not formed under >266Pa pressure and t.he rate of film formation is low under <2.66Pa pressure. When plasma polymn. time is >30min, the surfaces of the toner particles are deteriorated and the triboelectric chargeability is made inferior. By plasma polymn. under the above-mentioned conditions, a hard hydrophobic polyermized film can be formed on the surface of each of the toner particles so that the toner particles withstand use at high temp. and humidity.