1. A surface acoustic wave apparatus having 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 includes a first overlapping region with an 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 an overlapping length weighted in the propagation direction of the surface acoustic wave, and wherein an envelope curve of the overlapping-length weighted in the second overlapping region has at least two changing points in the propagation direction of the surface acoustic wave.