The invention provides a fixing device in which a fuser unit and an IH coil unit can be accurately positioned and an image forming apparatus. Embodiments include a fuser unit, a heating unit and a plate capable of mounting the both. A supporting shaft extending in the direction of a heating unit is provided on the plate. A first bracket configured to support, on the supporting shaft, a center portion in a longitudinal direction of the heating unit and allow the heating unit to move in a rotating direction and a vertical direction with respect to the plate is provided in the heating unit. Receivers are provided at both end portions in the longitudinal direction in one unit of the heating unit and the fuser unit. Inserters are provided in the other unit to be opposed to the receivers. If thefuser unit is mounted to the plate, the inserters are coupled to the receivers to restrict the heating unit from moving in the rotating direction and the vertical direction.