A surface acoustic wave device in which an X-cut LiTaO.sub.3 single crystal substrate has its one major surface coated with a SiO.sub.2 film and the direction of propagation of surface acoustic waves is selected between 80.degree. and 180.degree. measured from the Y-axis toward the Z-axis. The surface acoustic wave devices in accordance with the present invention has an extremely low temperature coefficient change and a high electro-mechanical coupling coefficient, exhibits a higher degree of both short- and long-term stability, and can suppress the generation of unwanted waves to a minimum or negligible degree.