An acoustic wave device includes a piezoelectric substrate and an IDT electrode provided on the piezoelectric substrate. In the IDT electrode, a central region, first and second low acoustic velocity regions and first and second high acoustic velocity regions are disposed in this order. A duty ratio in the first low acoustic velocity region of first electrode fingers and the second low acoustic velocity region of second electrode fingers is larger than a duty ratio in the central region. When acoustic velocity of a transversal bulk wave propagating in metal that is a main component of a main electrode layer is defined as v (m/s), v≤3299 m/s, and when a wave length defined by an electrode finger pitch of the IDT electrode is defined as λ, and a film thickness of the main electrode layer normalized by the wave length λ is defined as T, then T≥0.00018e0.002V+0.014.