A fixing device and image-forming apparatus, which provide required glossiness and paper adaptability, and, in addition, feature good operability and excellent durability while achieving optimal pressure-applying force for a variety of requirements, having: a pressure-applying lever; a pressure-releasing lever; a locking member, the one end of which is rotationally attached to the pressure-releasing lever; and an elastic member, which pulls the locking member in a locking direction. The configuration is such that the rotation of the pressure-releasing lever displaces the location of the locking member, thereby enabling switching between a pressure-applying position, in which a fixing member presses against another fixing member, and a pressure-releasing position, in which the one fixing member moves away from the other fixing member, and in the pressure-applying position, the pressure-applying lever and the locking member, which are fastened together at one end of the pressure-applying lever opposite a rotation central shaft, are pulled in a locking direction by the elastic member, and the gripping pressure on a piece of paper is varied by the pair of fixing members.