A toner for developing electrostatic images is provided which has good adhesion resistance and good low temperature fixing property, and further can exhibit good image developing performance in various quality aspects including fog resistance, filming resistance, and image density. The toner includes at least a binder resin and a colorant and is characterized in that the toner, prepared as such, has a melt index range of 15 to 40 (g/10 minutes) at 125.degree. C. and the binder resin has a melt index range of 3 to 12 (g/10 minutes) at 150.degree. C.