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; a region with the plurality of interleaved
comb-shaped electrodes is formed with two regions which are a first
overlapping region and a second overlapping region with
overlapping-lengths weighted along a propagation direction of a surface
acoustic wave; the first overlapping region and the second overlapping
region are in contact or overlapped in a direction vertical to the
propagation direction of the surface acoustic wave; and in either the
first or the second overlapping region, an overlapping-length weighting
envelope curve has at least two or more changing points in the
propagation direction of the surface acoustic wave.