A phase-change memory device in which a phase-change material layer has a multilayered structure with different compositions and a method of fabricating the same are provided. The phase-change memory device includes a first electrode layer formed on a substrate, a heater electrode layer formed on the first electrode layer, an insulating layer formed on the heater electrode layer and having a pore partially exposing the heater electrode layer, a phase-change material layer formed to fill the pore and partially contacting the heater electrode layer, and a second electrode layer formed on the phase-change material layer. The main operating region functioning as a memory operating region is formed of a Ge2Sb2+xTe5 phase-change material to ensure the stability of a memory operation, and simultaneously, the subsidiary regions formed of a Ge2Sb2Te5 phase-change material are disposed respectively on and under the Ge2Sb2+xTe5 main operating region to prevent leakage of thermal energy through an electrode, thereby reducing power consumption.