The surface acoustic wave device of the invention comprises a piezoelectric substrate made up of 64° rotated Y-cut lithium niobate (64LN) or 36° rotated Y-cut lithium tantalate (36LT) and an interdigital electrode formed thereon. The interdigital electrode comprises a titanium buffer metal film and an aluminum film formed thereon. On the 64LN substrate, both the titanium buffer metal film and the aluminum film are converted into a single-crystal film that manifests itself in a spot form alone upon selected-area electron diffraction. By forming the aluminum film on the 36LT substrate with the titanium buffer metal film located therebetween, it is possible to obtain a high-orientation, polycrystalline aluminum film oriented in the (111) direction. The aluminum film is made up of a single-crystal film or a high-orientation polycrystalline film oriented in the (111) direction, whereby migration of aluminum atoms is inhibited, resulting in a power-durability improvement.