An acoustic wave device includes an interdigital transducer (IDT) electrode and a separate electrode facing the IDT electrode. The IDT electrode includes first and second comb-shaped electrode facing each other. The first comb-shaped electrode includes a first bus bar, first interdigitated electrode fingers, and first dummy electrode fingers. The second comb-shaped electrode includes a second bus bar second interdigitated electrode fingers interdigitated with the first interdigitated electrode fingers, second dummy electrode fingers facing the first interdigitated electrode fingers, weighted parts, and a non-weighted part. The weighted parts have electrodes at spaces between the second interdigitated electrode fingers and the second dummy electrode fingers. In the non-weighted part, there is no electrode at a space out of the spaces which is closest to the separate electrode in the non-interdigitated region. This acoustic wave device prevents short circuits between the IDT electrode and the separate electrode, and provides excellent characteristics of suppressing unwanted waves.