Patent ID: 7800283

Claim:
A screw driving device for performing a tightening operation and a loosening operation on a screw with respect to a screw hole that is correspondingly formed in a member to be fastened, comprising: a device body in which are provided a piezoelectric element that generates predetermined ultrasonic oscillations upon being impressed with a predetermined alternating current, and an oscillating end surface on which mechanical oscillations are excited based on the ultrasonic oscillations; and an oscillation transmission means that is integrally fixed to the device body on the oscillating end surface and that transmits the mechanical oscillations to the screw by contact with the screw, wherein the oscillation transmission means includes a frictional material that is provided with a screw contact surface that is correspondingly formed to be capable of surface contact with a top end face formed on the screw head of the screw to transmit ultrasonic mechanical oscillations to the screw by frictional contact with the top end face.