Abstract: A transmission cable for use with an ultrasonic device such as an ultrasonic machining device is provided. The transmission cable of the present invention comprises a plurality of fine metallic wires coupled between the output terminal of an ultrasonic oscillation generating source and the input terminal of a terminal machining tool of the ultrasonic device. The metallic wires are covered with a flexible tubular member which may preferably be filled with a liquid so that the lateral vibrations of the wires are suppressed thereby. This type of cable is particularly advantageous in that the ultrasonic oscillations of the wires forming the cable can be transmitted efficiently to the terminal machining tool and the cable is suitable and convenient for carrying out the ultrasonic machining operations with the machining tool.