A fixing device includes a heating roller that is internally provided with a heat source member and is rotated by a drive unit; an endless fixing belt that is entrained around the heating roller and heated thereby, and is provided with a surface layer that contacts a recording medium, and the yield stress of a material forming the surface layer is varied according to the temperature of the material; a pressure member that is provided facing the heating roller and presses the recording medium, on which a toner image has been formed, against the fixing belt; a travel direction alteration member that contacts the fixing belt and changes the direction of travel of the fixing belt by bending the fixing belt; and a drive control section that operates the drive unit and rotates the heating roller after the heating roller has been heated such that the endless fixing belt is heated by the heating roller to a predetermined temperature where the yield stress of a material forming the surface layer of the fixing belt is larger than the stress acting on the surface layer when the travel direction of the fixing belt is altered by the travel direction alteration member.