An acoustic wave device includes a supporting substrate made of lithium tantalate, an element substrate made of lithium tantalate, and having a lower surface bonded to and arranged on an upper surface of the supporting substrate, and a comb-like electrode formed on an upper surface of the element substrate and exciting an acoustic wave. A propagation direction of the acoustic wave in the element substrate is an X-axis of the acoustic wave. A normal direction of the upper surface of the supporting substrate is an X-axis or a Y-axis of the supporting substrate. The propagation direction of the acoustic wave is not parallel to a Z-axis of the supporting substrate.