An acoustic wave device includes a support substrate, a piezoelectric film, a functional electrode, and a support. The support substrate includes a cavity. The piezoelectric film is provided on the support substrate to cover the cavity. The functional electrode is provided on the piezoelectric film to overlap the cavity when viewed in a plan view. The support is in the cavity of the support substrate to support the piezoelectric film. The functional electrode includes electrodes arranged in a direction crossing the thickness direction of the piezoelectric film. The electrodes include a first electrode and a second electrode. The first electrode and the second electrode oppose each other in a direction crossing the thickness direction of the piezoelectric film and are connected to different potentials. Adjacent ones of the electrodes overlap each other in a direction orthogonal to a longitudinal direction of the first electrode.