PURPOSE: To facilitate keeping of accurate high speed operation by exerting abrasion resistance for a long period by method wherein a surface treated part composed of a fluoropolyether polymer containing a specific main structural unit and average molecular weight is formed on a meshed surface of a heat resistant synthetic resin made gear.

CONSTITUTION: A surface treated part which is composed of fluoropolyether polymer of 1000-50000 average molecular weight having a main structural unit as given by the formula -CxF2x-O [x is an integer of 1-4], is formed on a meshed surface of a heat resistant synthetic resin made gear 4. In a fixing apparatus A, the heat resistant synthetic resin has heat resistance of ordinary continuous service temperature (about 200°C), and preferably a polyphenylene sulfide resin, a polyimide resin, a polyamide-imide resin, an aromatic polyester resin, a nylon 66 resin, a nylon 46 resin, and a polyetherimide resin are used. Then, a fibrous reinforcement may be added to those heat resistant synthetic resins.