A polyester resin for toner, wherein an acid component of the polyester comprises (1) disproportionated rosin and (2) terephthalic acid and/or isophthalic acid, an alcohol component of the polyester comprises (3) glycidyl ester of tertiary fatty acid and (4) an aliphatic diol containing from 2 to 10 carbon atoms, and a cross-linking component of the polyester comprises a polycarboxylic acid having three or more carboxyl groups and/or a polyol having three or more hydroxyl groups, with the molar ratio of the acid component (1) to the acid component (2), (1)/(2), being from 0.2 to 0.6 and the molar ratio of the alcohol component (3) to the alcohol component (4), (3)/(4), being from 0.05 to 0.4. A toner for developing an electrostatic charge image contains the polyester resin for a toner (binder resin), a colorant and a charge control agent. Further, the invention also relates to an image-forming method using the toner for developing an electrostatic charge image.