An acoustic wave device includes first and second 3-IDT acoustic wave filters provided on a piezoelectric substrate. A second IDT in the first acoustic wave filter is electrically connected to a second IDT in the second acoustic wave filter and a third IDT in the first acoustic wave filter is electrically connected to a third IDT in the second acoustic wave filter to cascade the first acoustic wave filter with the second acoustic wave filter. An acoustic wave resonator is connected to a first IDT in the first acoustic wave filter. In the acoustic wave device, NA/NB is in a range from about 2.6 to about 3.5 and fB/fa is in a range from about 0.995 to about 1.010, where NA denotes the number of electrode fingers of the first IDT in the first acoustic wave filter, NB denotes the number of electrode fingers of each of the second and third IDTs in the first acoustic wave filter, fB denotes the end frequency of a stop band of each of reflectors in the first and second acoustic wave filters, and fa denotes an anti-resonant frequency of the acoustic wave resonator.