<p>A surface acoustic wave device comprising a single crystal silicon substrate (1) and a piezoelectric thin film of single crystal or C-axis-oriented polycrystalline aluminum nitride (2) formed on the crystal of the substrate. The C-axis of the piezoelectric thin film is set in a direction in which the projection vector (22) of the C-axis (21) on a plane containing the axis of propagation direction of a surface acoustic wave and a normal axis of the substrate makes an inclination angle theta of up to 60 degrees with the axis of propagation direction, whereby the device is given a coupling coefficient of at least 2% is given as maximum coupling coefficient of the device.</p>
