An elastic wave device includes a LiNbO3 substrate, an IDT electrode provided on the LiNbO3 substrate, and a dielectric film that is provided on the LiNbO3 substrate so as to cover the IDT electrode and includes a projection on an upper surface of the stated dielectric film. A main mode of an elastic wave excited by the IDT electrode uses a Rayleigh wave, and a thickness of the IDT electrode is set such that a frequency at which a response by an SH wave appears is lower than a resonant frequency of the Rayleigh wave.