Disclosed herein is a fusing device having an improved heating structure. The fusing device is configured to apply heat and pressure to fix a developer to a print medium and includes a pressure device and a heating device. The heating device includes a heat radiating member extending along a longitudinal direction of the fusing device and terminal parts disposed at both ends of the heat radiating member. Contact points at which current is supplied to the heat radiating member through the terminal parts can be adjusted to change the effective width of heating area.