Toner for developing electrostatic image and image forming method

A toner for developing an electrostatic image is disclosed which has at least one endothermic peak in the temperature region of 120 DEG C or below in differential thermal analysis and contains, in its particles having particle diameters of 3 mu m or larger, not less than 90% by number of particles having a circularity of at least 0.90 and less than 30% by number of particles having a circularity of at least 0.98. The toner does not cause the re-transfer under high transfer current conditions and can realize the formation of good images with high image density. Also, an image forming method using the toner is disclosed.