To provide acoustic wave devices in each of which the frequency positions of higher modes that propagate in a support substrate made of silicon hardly vary.SOLUTION: An acoustic wave device 1 includes: a support substrate 2 made of silicon; a piezoelectric body 4 provided directly or indirectly on the support substrate 2, the piezoelectric body including a pair of main surfaces facing each other; and an IDT electrode 5 provided directly or indirectly on at least one of the main surfaces of the piezoelectric body 4, where a wave length that is determined by an electrode finger pitch of the IDT electrode being λ. An acoustic velocity VSi in the following expression (1) of bulk waves that propagate in the support substrate 2 is higher than or equal to 5,500 m/s, the acoustic velocity being determined by V1 out of solutions V1, V2, V3 of x derived from the following expression (2). VSi=(V1)1/2...expression (1) Ax3+Bx2+Cx+D=0...expression (2)SELECTED DRAWING: Figure 1