PURPOSE: To obtain a large speed reduction ratio and achieve the miniaturization of the device with a simple mechanism by providing an eccentric cam interlocking to a high-speed revolving member and an oscillating plate via clutch to a low-speed revolving member and engaging these.

CONSTITUTION: A spur gear 5 is fixed to one end of the revolving shaft 3a of magnet, and one end of the magnet roll 1 is supported via bearing 6 to a side plate 7. On the other hand, a roll clutch 8 which revolves in one direction only is press-fitted to the other end of the roll 1 concentrically with the revolving shaft 3a. A drive shaft 11 is supported to the side plate 7 by way of a bearing 14 and the shaft 11 is connected to an eccentric cam 15 which has the axial center coaxial to the shaft 11, by means of a pin 17. The eccentric cam 15 is supported to a side plate 10 by way of a bearing 14. further the eccentric cam 15 is connected to a high-speed revolving body side drive shaft 18 by means of a pin 16. This enables a large speed reduction ratio to be obtained by using one driving source with the simple mechanism.