PURPOSE: To provide a friction driving device for highly precisely feed-driving a driver by keeping a vertical drag generated between a feed body and the driver constant.

CONSTITUTION: A driver 6 pressed onto a rotated and driven feed body 3 with a determined pressure is formed by a strong dielectric displacement element deformed by applying an electric field. A vertical drag generated by the contact of the driver 6 with the feed body 3 is detected by a strain gauge 15, and according to the detection signal detected by the strain gauge 15, the electric field to be applied to the driver 6 is controlled. Thus, the vertical drag between the feed body 3 and the driver 6 is kept constant.