Acoustic wave device

An acoustic wave device comprising:

• a piezoelectric layer;
• an interdigital transducer (IDT) electrode on the piezoelectric layer, and including a plurality of electrode fingers;
• and
• a dielectric film on the piezoelectric layer and covering the IDT electrode;
• wherein
• when viewed in a direction orthogonal or substantially orthogonal to a direction in which the plurality of electrode fingers extend, an area where adjacent two or more of the plurality of electrode fingers overlap one another is an intersecting area;
• the acoustic wave device further includes a thin-film layer at least a portion of which is embedded in the dielectric film, at least a portion of which overlaps the intersecting area in a plan view, an entirety or substantially an entirety of which does not overlap the plurality of electrode fingers in a plan view, having a higher density than the dielectric film, and having a smaller thickness than the plurality of electrode fingers;
• and
• the plurality of electrode fingers and the thin-film layer are located at different positions in a thickness direction of the dielectric film.