Abstract: The elastic wave device of the present invention has an piezoelectric substrate; a first dielectric layer disposed on the piezoelectric substrate; a second dielectric layer disposed on the first dielectric layer; and an acoustical layer on the second dielectric layer. Determining each film thickness of the first and the second dielectric layers provides advantageous effects. That is, energy of an SH wave as a main wave is confined in the boundary between the piezoelectric substrate and the first dielectric layer, and at the same time, an SV wave is suppressed as an unwanted wave. The device allows the SV wave—whose displacement distribution is similar to that of Stoneley wave—to have displacement distribution on the upper surface of the second dielectric layer and to be suppressed by the acoustical layer disposed on the second dielectric layer.