Abstract: The invention provides a grease composition for use in an image forming apparatus, containing a thickener, a base oil and a lubricity improver, wherein the thickener is a lithium soap, the base oil is a synthetic hydrocarbon oil, the lubricity improver is a polyethylene oxide wax, and the image forming apparatus is equipped with a sliding member and a member for holding the sliding member which is driven to slide through the holding member via the grease composition, one of the sliding member or the holding member for the sliding member having a sliding surface formed from a metal, and the other having a sliding surface formed from a resin.