An acoustic wave element according to certain examples includes a piezoelectric body, an interdigital transducer (IDT) electrode disposed above the piezoelectric body, and a connection electrode disposed above the piezoelectric body and connected to the IDT electrode. A first insulation layer covers the connection electrode, and a second insulation layer covers the IDT electrode. The first insulation layer disposed above the connection electrode has a first thickness T in a direction perpendicular to an upper surface of the piezoelectric body and the second insulation layer disposed above the IDT electrode has a second thickness K in the direction perpendicular to the upper surface of the piezoelectric body. The first thickness T is less than the second thickness K.