Fixing device

A fixing device that fixes a toner image to a recording material by heating the toner image borne on the recording material, the fixing device comprising:

• a rotatable endless belt member;
• a heating roller disposed inside the belt member, and configured to stretch the belt member and heat the belt member;
• a steering roller disposed inside the belt member, and configured to stretch the belt member together with the heating roller and control a position of the belt member with respect to a rotation axis direction of the heating roller by tilting with respect to the rotation axis direction;
• a nip portion forming member contacting an outer peripheral surface of the belt member, and configured to form a nip portion for nipping and conveying the recording material between the nip portion forming member and the belt member;
• and
• a cover member disposed with a gap from the belt member in such a manner as to cover a part of an outer side of the belt member,
• wherein the belt member has a region in which a distance from the cover member changes in a case where the steering roller tilts with respect to the heating roller and the region includes a first stretched region stretched by the steering roller and a second stretched region stretched by the heating roller, and
• wherein, in a cross-section orthogonal to a rotational axis of the heating roller, in a state where a first virtual line is defined as a line passing through a rotation center of the steering roller and being parallel to a tilting direction of the steering roller, a point P is defined as a point where the first virtual line crosses an inner surface of the cover member above the belt member, and a point Q is defined as a closest point on the belt member from the point P, the cover member is disposed in such a manner that a length of a line segment PQ between the point P and the point Q is a first length when the steering roller is parallel to the heating roller and an average distance between the cover member and the second stretched region is a second length that is shorter than the first length.