In a dual-side image formation, a fixing apparatus has a fixing member for fixing an image on the recording material by heat, a heat supply member for supplying heat from the exterior of the fixing member, and a dual-side image forming unit which forms images on both sides of the recording material. A first image forming operation for forming an image on a first side of the recording material and a second image forming operation for forming an image on a second side of the recording material are executed repeatedly and a heat supply control controls heat supplied to the fixing member so that a heat supplying condition of the heat supply member is changed according to the side of the recording material when an image is fixed thereon.