The IDT electrode has the first bus bar and second bus bar; the plurality of first electrode fingers and the plurality of second electrode fingers mutually intersect; the plurality of first dummy electrodes and the plurality of second dummy electrodes which have front ends facing front ends of the plurality of first electrode fingers and the plurality of second electrode fingers with the gap s1; the plurality of first auxiliary electrodes which protrude laterally from the front end side portions of the pluralities of first dummy electrodes; and the plurality of second auxiliary electrodes which protrude laterally from the front end side portions of the plurality of second dummy electrodes. The plurality of first auxiliary electrodes have edge portions located a side of the second bus bar. The edge portions are located a side of the second bus bar the more to a side of the front end.