An acoustic wave device includes a substrate, a multilayer film on the substrate, an LT layer which is located on the multilayer film and is configured by a single crystal of LiTaO3, and an IDT electrode on the LT layer. In the multilayer film, a differential value obtained by subtracting a total value of values each obtained by multiplying a density and thickness of a film having a slower acoustic velocity than a transverse wave acoustic velocity of the LT layer from a total value of values each obtained by multiplying a density and thickness of a film having a faster acoustic velocity than the transverse wave acoustic velocity of the LT layer is negative, and a thickness of the LT layer is less than p and a thickness of the multilayer film is less than p where a pitch of electrode fingers in the IDT electrode is “p”.