An acoustic wave device includes a support substrate, a piezoelectric body, an acoustic layer laminate, first and second electrodes, and a lead-out electrode. The first electrode is on a first main surface of the piezoelectric body, the second electrode is on a second main surface of the piezoelectric body, the lead-out electrode is on the first main surface or the second main surface of the piezoelectric body, the lead-out electrode is electrically connected to the first electrode or the second electrode, side surface grooves extend from the first main surface side of the piezoelectric body, and the side surface grooves are provided in at least a portion of a remaining portion excluding a portion provided with the lead-out electrode from a region in an outer side portion of at least one of the first electrode and the second electrode.