FIXING DEVICE

PURPOSE:To provide a fixing device of an inexpensive constitution capable of preventing a fixing belt from oblique movement of the fixing belt itself. CONSTITUTION:The fixing belt 53 is provided so as to circularly running between a heating roll 51 and a separating roll, and a toner image is fixed by running a transferred material formed with the toner image through the opposing gap between the fixing roll 53 and a pressure roll 11. A concave roll is also provided as a pressure roll 11. By the rotation of the pressure roll 11, the force stretching the fixing belt 53 toward the both end side (the force widening the width of the fixing belt toward the left and the right) are uniformly generated, thus, its oblique movement or looseness is prevented from occurrence.