A fixing device includes a heat roller and a heater. The heat roller extends in an axial direction and includes a cylindrical-shaped roller section and a coil, the roller section having an inner peripheral surface defining an internal space therewithin and the coil being wound along the inner peripheral surface, the heat roller being configured of a plurality of zones in the axial direction, the plurality of zones including a low zone whose heat capacity is less than a predetermined value and a high zone whose heat capacity is not less than the predetermined value. The heater is disposed within the internal space of the roller section and has a heating wire configured to generate heat, the heating wire having at least a first portion which is in confrontation with the high zone and a second portion which is in confrontation with the low zone, and the heating wire being configured such that the first portion has an amount of heat generation greater than an amount of heat generation at the second portion.