A surface acoustic wave apparatus has a configuration by which the
spurious of the higher-order transverse modes is suppressed and a SAW
excitation intensity distribution is not changed in the propagation
direction. The surface acoustic wave apparatus has at least one
interdigital transducer, which is disposed such that a plurality of
comb-shape electrodes respectively connected to common electrodes are
interleaved, wherein a region with the plurality of interleaved
comb-shape electrodes has a first overlapping region with a overlapping
length constant over a whole area along a propagation direction of a
surface acoustic wave and a second overlapping region formed on at least
one side of the first overlapping region with a overlapping length
weighted in the propagation direction of the surface acoustic wave, and
wherein an overlapping-length weighting envelope curve in the second
overlapping region has at least two changing points in the propagation
direction of the surface acoustic wave.