FIXING UNIT AND IMAGE FORMING DEVICE

PROBLEM TO BE SOLVED: To provide a fixing unit configured to reduce backlash of a cylindrical member when releasing pressure, and to provide an image forming device.SOLUTION: A fixing unit includes: a cylindrical member to be elastically deformed; a pressed member to be pressed against the cylindrical member; a heat source held between the cylindrical member and the pressed member to heat a recording medium; a first member having at least an inner surface of a curvature radius larger than the radius of a cylindrical shape of the cylindrical member, allowing the cylindrical member to be pressed against the inner surface by the pressed member pressed to the cylindrical member, and supporting the elastically deformed cylindrical member on the inner surface so as to rotate in a circumferential direction; a release unit for releasing the pressed member pressed against the cylindrical member; and a second member that comes closer to the cylindrical member during restoration than during elastic deformation, or a third member which does not move its position during elastic deformation and restoration, and supports a part of the cylindrical member.