A surface acoustic wave device comprises lithium tetraborate single crystal substrate to make use of surface acoustic waves with higher propagation velocities and smaller propagation losses, whereby frequencies to be signal-processed can be as high as above 1 GHz. The surface acoustic wave device comprises a metal film formed on a surface of a lithium tetraborate single crystal substrate, the metal film being for exciting, receiving, reflecting and/or propagating surface acoustic waves, the metal film being so formed that a cut angle of the substrate, and a propagation direction of the surface acoustic waves are in an Eulerian angle representation of (39.degree.-51.degree., 66.degree.-114.degree., -20.degree.-20.degree.) and directions equivalent thereto. In this propagation direction few Rayleigh waves exit, and only surface acoustic waves of high propagation velocity are generated. Propagation losses can be eliminated.