A fixing device includes a heating roller, a pressing roller, a heating part, a heat insulating member and a bearing. The pressing roller holds a sheet with the heating roller. The heating part heats the heating roller. The heat insulating member is fitted on an end portion in an axial direction of the heating roller, has a heat-resistance to heat applied from the heating roller and has an inclined shape in which an outer diameter becomes small toward an inside in the axial direction of the heating roller. The bearing supports the heating roller through the heat insulating member.