TONER OF ELECTROPHOTOGRAPHY

PURPOSE: To obtain an image high in color density and sharp in outlines and low in susceptibility to humidity and good in heat stability by developing an electrostatic image with the electrophotographic toner containing a specified additive and increasing a cationic charge. CONSTITUTION: The toner has a cationic charge increased and contains the additive represented by formula I in which each of (X ) and (X ) is, independently, an anion; each of K and K is, independently, a group of formula II; R is a 1-22 C alkyl group or a benzyl group or the like; R is an H atom or the like; R is a 1-4 C alkyl group; each of Y and Y is, independently, a 2-5 alkylene group or the like; and A is a tetracarbonyldiimide group represented by formula III or a 3-amino-1-iminoisoindolenine group represented by formula IV, and these cyclic and acyclic groups each can have an ordinary nonionic substituent, thus permitting the developed image to be increased in its color density and to be improved in its sharpness and to be lowered in susceptibility to high atmospheric humidity and to be extended in the usable life of the toner.