PURPOSE: To prevent the generation of deflection and permanent strain on a rotary shaft by reducing the weight of a magnetic rotary body made by sleeve members.

CONSTITUTION: When a pulley is installed on each shaft of a transport roller and a roller for driving a photosensitive material, and a fixation roller 201, they are not directly installed, and installed through sleeve members 47-49. As the sleeve member, is preferable the resin group material. Further, when the sleeve part and the metal part of an outside magnetic body are integrally shaped through press fitting, adhesion, etc., the number of parts can be reduced, and easy handling is enabled.