A surface acoustic wave device includes a ZnO dielectric thin film on a quartz substrate and an IDT electrode having strips between the ZnO thin film and the quartz substrate. The IDT electrode has at least one region where the strips are disposed at an interval defined by approximately a half-wavelength of the surface acoustic wave. The duty ratio of the IDT electrode is preferably more than about 0.5. Alternatively, a protrusion is formed via a slope in the region of the ZnO thin film where the IDT electrode is disposed, and the inclination angle .theta. of the slope is more than about 30.degree..