A surface acoustic wave device includes a LiNbO.sub.3 substrate with a Euler angle in an area defined by a rectangle having four corners with coordinates (1) (0.degree., 7.degree., 101.degree.), (2) (0.degree., 23.degree., 79.degree.), (3) (0.degree., 23.degree., 79.degree.), and (4) (0.degree., 7.degree., 79.degree.), for example, and an electrode film made of Au, wherein surface acoustic waves including a longitudinal wave component as a main component are propagated thereon. The surface acoustic wave device uses longitudinal surface acoustic waves having a phase speed greater than with the "slow transverse wave", and has a great electromechanical coupling coefficient and small propagation loss, and is suitable for handling high-frequency signals.