A fusing device for an image forming apparatus configured to apply heat and pressure to a recording medium passing through a fusing nip, the fusing device comprising: a heating roller (110, 110a, 110b) disposed to contact a surface of the recording medium to transfer heat thereto; an endless belt disposed to rotate together with the heating roller (110, 110a, 110b); and a pressing member to press an inner surface of the endless belt to allow the fusing nip to be formed between the heating roller and the endless belt, wherein the heating roller (110, 110a, 110b) comprises: a shaft formed in a cylindrical shape; a heat-generating layer disposed to surround the shaft which consists of an electrical resistor to generate heat when current is supplied thereto to heat the recording medium passing through the fusing nip; an electrical insulating layer disposed between the shaft and the heat-generating layer to electrically insulate the heat-generating layer and the shaft; and a release layer disposed to surround the heat-generating layer and adapted to prevent the recording medium passing through the fusing nip from sticking to the heating roller (110, 110a, 110b); characterized in that the pressing member is formed to have a shape approximately corresponding to a portion of an outer surface of the heating roller (110, 110a, 110b). a heating roller (110, 110a, 110b) disposed to contact a surface of the recording medium to transfer heat thereto; an endless belt disposed to rotate together with the heating roller (110, 110a, 110b); and a pressing member to press an inner surface of the endless belt to allow the fusing nip to be formed between the heating roller and the endless belt, wherein the heating roller (110, 110a, 110b) comprises: a shaft formed in a cylindrical shape; a heat-generating layer disposed to surround the shaft which consists of an electrical resistor to generate heat when current is supplied thereto to heat the recording medium passing through the fusing nip; an electrical insulating layer disposed between the shaft and the heat-generating layer to electrically insulate the heat-generating layer and the shaft; and a release layer disposed to surround the heat-generating layer and adapted to prevent the recording medium passing through the fusing nip from sticking to the heating roller (110, 110a, 110b); characterized in that the pressing member is formed to have a shape approximately corresponding to a portion of an outer surface of the heating roller (110, 110a, 110b). a shaft formed in a cylindrical shape; a heat-generating layer disposed to surround the shaft which consists of an electrical resistor to generate heat when current is supplied thereto to heat the recording medium passing through the fusing nip; an electrical insulating layer disposed between the shaft and the heat-generating layer to electrically insulate the heat-generating layer and the shaft; and a release layer disposed to surround the heat-generating layer and adapted to prevent the recording medium passing through the fusing nip from sticking to the heating roller (110, 110a, 110b); characterized in that the pressing member is formed to have a shape approximately corresponding to a portion of an outer surface of the heating roller (110, 110a, 110b).