A fixing device may include a metal plate, an endless belt, a rotating body, and a stay. The metal plate may have a main part comprising a first end portion, a second end portion, and a center portion positioned therebetween and having rigidity higher than that of the first end portion and the second end portion. The endless belt may have an inner peripheral surface configured to be in sliding contact with the metal plate. The main part may be aligned with the rotating body in a direction from the metal plate to the rotating body. The stay may be disposed opposite to the nip region with respect to the metal plate. The stay and the main part of the metal plate may be deformable upon application of the load to the stay such that the main part may provide a convex shape protruding toward the rotating body.