A method of producing a toner for developing electrostatic charge image, the method comprising: aggregating particles containing a crystalline polyester resin, particles containing a non-crystalline polyester resin and particles of a releasing agent in an aqueous medium, so as to form aggregated particles; and heating the aggregated particles to fuse into a coalescent body, wherein at least one of the crystalline polyester resin and the non-crystalline polyester resin is obtained by polymerization at temperatures not higher than 150.degree. C. with a Bronsted acid containing a sulfur atom as a catalyst, and wherein a first onset temperature A(.degree. C.) of the toner and a glass transition temperature B(.degree. C.) of the non-crystalline polyester resin as measured by differential scanning calorimeter satisfy a relation (B-A).ltoreq.10, and wherein a weight average molecular weight of the crystalline polyester resin is 1/2 or lower of a weight average molecular weight of the non-crystalline polyester resin.