Toner for developing an electrostatic image, which satisfies charging stability, low-temperature fixability, high-temperature storage characteristics, and durability with respect to an environment up to a predetermined level or above, and a method of preparing the toner. The toner includes: a core layer including a first binder resin, a colorant, and a releasing agent; and a shell layer covering the core layer and including a second binder resin, wherein the first binder resin includes about 70 wt % or above of amorphous polyester resin and about 30 wt % or below of crystalline polyester resin, the second binder resin includes an amorphous polyester resin, and a melting temperature (Tm(C)) of the crystalline polyester resin, a melting temperature (Tm(W)) of the releasing agent, and a melting point (Tm(T)) of the toner satisfy the following conditions: −20° C.≦Tm(W)−Tm(C)≦20° C.; and 0° C.