The present invention provides a fixing device that has a planar member including a heat conduction layer. The heat conduction layer has a predetermined thickness and relatively pressed against a rotary member being rotated so that the device fixes an unfixed toner image born by a recording sheet onto the recording sheet by causing the sheet bearing the unfixed toner image to pass between the planar member and the rotary member and applying heat and pressure to the unfixed toner image. The device includes a heater that applies heat to the unfixed toner image born by the sheet passing between the planar member and rotary member. The heat conduction layer includes a heat conduction anisotropic material whose heat conduction coefficient showing the degree of easiness of heat conduction in a surface direction in which the heat conduction layer extends is larger than that in a thickness direction.