A method and apparatus for measuring the force applied by a first member 25 coupled to a second member 26 by a connecting body 6 by transmitting a cyclically-rrepeating energy wave through the connecting body from a first location thereon to a second location thereon, measuring the transit time of the cyclically-repeating energy wave from the first location to the second location and utilizing the measuring transit time to produce a measurement of the force. In the preferred described embodiment, the connecting body is a fastening plate 6 which fastens a drive shaft 3 to a driven shaft 5 and measures the torque output of the drive shaft.