A fixing device has a fixing roller including an inside roller, an outside roller and a regulation member. The regulation member is disposed outside of both ends of the outside roller in the axial direction to regulate axial movement of the outside roller. An axial length of the contact face, where the pressure roller contacts with the outside roller, is smaller than an axial length of the outside roller. Thereby, both ends of the outside roller hardly receive bending deformation caused by pressure of the pressure roller. This makes it possible to reduce stress exerted to both ends of the outside roller, and therefore, the ends of the fixing roller are prevented from being damaged to enhance durability of the fixing roller.