PURPOSE: To release the temperature rise of a member to be driven, to reduce wearing and to improve an operation rate by providing a means for generating an air current by means of the rotation of a fixing roller supporting and rotary shaft and cooling the member to be driven.

CONSTITUTION: A fixing gear 17a which is the member to be driven and a ventilating member 17b which consists of ventilating propellers which generate an air current due to the rotation of the supporting and rotary shaft 16 are mounted on the edging part of the supporting and rotary shaft 16 for the fixing roller 13. When the fixing roller 13 is rotated and driven by the fixing gear 17a, the ventilating member 17b is also rotated and wind is sent to the gear 17a to cool it. Thus the temperature of the gear 17a is lowered and wearing is reduced. Then the operation rate is improved.