A fuser unit includes: a cylindrical member; a heat generator; a nip member; a backup member, which configures a nip part between the cylindrical member and the backup member with the cylindrical member; a conductive member, which is arranged to cover the heat generator at the inside of the cylindrical member; a temperature detection unit; a wiring; a first frame having insulation, which is arranged at an opposite side to the heat generator with respect to the conductive member being interposed therebetween at the inside of the cylindrical member, and which extends along the conductive member; and a second frame, which is arranged at an opposite side to the conductive member with respect to the first frame being interposed therebetween at the inside of the cylindrical member, and which extends along the first frame, wherein the wiring is arranged between the first frame and the second frame.