An image forming apparatus includes a fixing device that forms a fixing nip by a pressure rotator and a fixing belt that rotates while contacting the pressure rotator, and includes: a nip former that is disposed inside the fixing belt and that forms the fixing nip between the pressure rotator and the fixing belt; and a lubricant supplier that forms a lubricant-retaining space at a position between an inner surface of the fixing belt and the nip former on an upstream side of the nip former in a rotation direction of the fixing belt, wherein the lubricant supplier varies a volume of the lubricant-retaining space.