A fixing device includes first and second rotatable members configured to fix, at a nip therebetween, a toner image formed on a sheet by using a toner containing a parting agent; a casing provided with a sheet introducing opening and a sheet discharging opening and configured to include the first and second rotatable members; a fan; a duct configured to guide air from the fan toward one longitudinal end portion of the first rotatable member; and a cover member configured to cover an outer surface of the first rotatable member, wherein the cover member extends inside the casing from a neighborhood of the sheet introducing opening to the duct.