To provide an image forming apparatus including a fixing device capable of controlling heater temperature to be low, and also, capable of preventing offset even at the low controlled temperature.

The image forming apparatus includes the fixing device wherein a recording material P carrying an unfixed toner image is guided into between the outer surface of a fixing film 22 and a pressure member 11 at a fixation nip portion N, and the recording material P is moved to pass through the fixation nip portion N together with the fixing film 22, then, the heat of a heating body 100 is applied to the recording material P through the fixing film 22. The circumferential length of the fixing film 22 is set longer than the length of the longest recording material P usable in the image forming apparatus, and also, at a point of time when almost the downmost stream end of the recording material P reaches the fixation nip portion N, the recording material P is switched back, then, discharged outside the apparatus, the downmost stream side of the recording material P being discharged first.