PURPOSE: To improve mechanical property at normal temp., to enhance impact resistance and toughness and triboelectrification characteristics, and to improve development performance by reacting a binder resin with a decomposable metal compd. to form a kind of a cross-linked state.

CONSTITUTION: A polyester resin produced from etherified bisphenol, polycarboxylic acids composed essentially of trivalent or higher valent polycarboxylic acids, and alkyl-substd. dicarboxylic acids is used for the binder resin of an electrostatic charge image-developing toner, and the decomposable metal compd. is reacted with this resin. The melt index (M.I.) of this binder resin alone is in the range of 1.0W50.0g/10min in the measuring conditions of 125°C and a load of 2.16kg, and the M.I. of the reaction product of the resin and the metal compd. is in the range of 0.1W15.0g/10min in the measuring conditions of 125°C and a load of 10kg. As the decomposable metal compd., metal ions having ≥ one valence, e.g., proper monovalent metal ions, such as Na+ and Cu+, proper divalent metal ions, such as Be2+ and Zn2+, and proper trivalent metal ions, such as Al3+ and Y3+, are enumerated.