Elastic wave device

The invention provides an elastic wave device capable of promoting miniaturization. An elastic wave device (10) is provided with: a support member (13); a piezoelectric layer (14) having a first main surface (14a) and a second main surface (14b) positioned on the support member (13) side; a first IDT electrode (11A) provided on the first main surface (14a) and having a plurality of first electrode fingers (26) and second electrode fingers (27); and a second IDT electrode (11B) provided in a portion of the second main surface (14b) that does not overlap the first IDT electrode (11A) in plan view, the second IDT electrode (11B) having a plurality of first electrode fingers (28) and second electrode fingers (29). The thickness of the piezoelectric layer (14) is d, and the distance between the centers of adjacent electrode fingers is p, in the first IDT electrode (11A) and the second IDT electrode (11B), d/p is 0.5 or less. The semiconductor device is further provided with: an insulating film (17) provided on a p