Acoustic wave device, filter, and duplexer

Acoustic wave device includes: a piezoelectric substrate; a first IDT located on the piezoelectric substrate; and a second IDT located on the piezoelectric substrate and connected in series to the first IDT, wherein the first IDT and the second IDT share a single common bus bar as a first bus bar of two bus bars of the first IDT and a first bus bar of two bus bars of the second IDT, and the common bus bar has a width not more than two times a wavelength of an acoustic wave propagating through the first and second IDTs, the common bus bar connects to no dummy electrode finger facing a tip of an electrode finger connected to a second bus bar of the two bus bars of the first IDT and the second IDT across a gap.