Provided is an elastic wave device which is unsusceptible to leaking elastic waves in a direction that is perpendicular to a lamination direction of a piezoelectric substrate. This elastic wave device 1 comprises: a piezoelectric substrate 2 having a piezoelectric layer 5 and provided with a hollow portion 10; and first and second electrodes 6, 7. In a plan view, the piezoelectric layer 5 has a first region A overlapping with the first and second electrodes 6, 7 and the hollow portion 10, a second region B not overlapping with the hollow portion 10 and surrounding the first region A, and a third region C overlapping with the hollow portion 10 and positioned between the first and second regions A, B. The cross-sectional shape of the piezoelectric substrate 2 along the lamination direction has a curved shaped at a portion including a boundary D of the first and third regions A, C. When the maximum value of the thickness of the piezoelectric layer 5 in the first region A is defined as t1M, and the thickness in the second region B is defined as t2, the relationship between t2 and t1M at a portion positioned in the second region B at least at a boundary with the third region C is t1M>t2.
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