Image forming apparatus for performing fixing processing by induction heating system

An image forming apparatus includes a first housing, a second housing on which the first housing is mounted, a first roller, a second roller, a nipping pressure adjusting mechanism, an induction heating unit and a retaining mechanism. A first rotary shaft of the first roller is rotatably supported by the first housing in a state of being positionally immovable. A second rotary shaft of the second roller is rotatably supported by the first housing in a state of being positionally movable. The nipping pressure adjusting mechanism changes the posture of the second roller between a first posture that the second roller is pressingly contacted with the first roller with a first pressure, and a second posture that the second roller is pressingly contacted with the first roller with a second pressure lower than the first pressure. The relative positions between the second roller and the induction heating unit are retained.