PURPOSE: To perform cooling of a heat source at a low cost by providing a fan part for generating an air stream to cool the heat source in one body with a rotational body for transmitting a drive force to a rotation mechanism part, near the heat source in a device.

CONSTITUTION: A gear 13 is disposed between a drive force transmitting system and a gear 12 for transmitting the drive force of a drive motor 11 to a rotation mechanism part of a device. The gear 13 having a boss 14 and a gear tooth formed portion 15 is connected into one piece to a fan portion 17 for arranging a plurality of blades 16 at equal intervals in the circumferential direction. That is to say, one edge portion of the inner peripheral diameter of the fan portion 17 is connected to the boss 14, the other edge portion of the outer peripheral side thereof is connected to the gear tooth formed portion 15. When the gear 13 near a driving motor 11 is rotated by the driving motor 11, a wind indicated by arrows is generated by the fan portion 17, and the driving motor 11 is cooled by the air stream. Consequently, heat diffusion near the heat source is promoted without any extra fan.