An elastic wave device includes a piezoelectric substrate with first and second main surfaces internally facing each other, an elastic-wave element that includes an interdigital transducer electrode provided on or in the first main surface of the piezoelectric substrate, and a first protective film that is provided on the first main surface of the piezoelectric substrate so as to cover the IDT electrode. The IDT electrode includes a main electrode layer made of a metal having a density higher than that of the first protective film. The piezoelectric substrate has a thickness of about 0.35 mm or smaller, and irregularities are located on the second main surface.