Abstract: The surface acoustic wave device of the invention comprises a piezoelectric substrate of lithium niobate or lithium tantalate and electrodes formed on the substrate for propagating surface acoustic waves. The substrate has a cut plane and a surface acoustic wave propagation direction which are (.phi., .theta., .psi.) as expressed in Eulerian angles and within ranges substantially equivalent thereto. When the substrate is made of lithium niobate, .phi., .theta. and .psi. are 0.degree.-86.degree. or 95.degree.-180.degree., 73.degree.-118.degree. and 0.degree.-44.degree., respectively. When the substrate is made of lithium tantalate, .phi., .theta. and .psi. are 0.degree.-87.degree. or 91.degree.-180.degree., 80.degree.-120.degree. and 0.degree.-44.degree., respectively. This enables the device to exhibit high performance.