A surface acoustic wave device in the present invention is provided with a
piezoelectric substrate, a supporting substrate being jointed to the
piezoelectric substrate and including a material different in expansion
coefficient from the piezoelectric substrate and an interdigital
electrode for exciting a surface acoustic wave, the electrode being
arranged on the surface of the piezoelectric substrate. Either the
interdigital electrode or the piezoelectric substrate is configured so
that the interdigital electrode is 40% or more to 70% or less as long as
the piezoelectric substrate in the direction to which a surface acoustic
wave propagates.