To obtain a device having high heat efficiency and produced at low cost by constituting a core member so that it may be divided into plural by a plane inclined at a specified angle to a plane perpendicular to the surface of a member to be fixed and parallel in carrying direction.

The core member is constituted so that it may be divided into plural by the plane inclined at the specified angle to the plane perpendicular to the surface of the member to be fixed and parallel in the carrying direction. In this device, a conductor roller 11 consists of iron, and the device is equipped with an exciting coil as a magnetic field generating means and the core members 21 and 22 for effectively controlling magnetic flux generated by the coil inside. The core members 21 and 22 are constituted by the use of a mold. In the case of molding, draft is required for the ends of the core members 21 and 22. In such a case, the ends of the core members 21 and 22 require a gradient being the angle of ≤5° to the plane perpendicular to the surface of the member to be fixed. In this device, two or more core members 21 and 22 are connected by adhesion with an adhesive 23, and constituted to support a gap formed with the roller at both ends.