A piezoelectric device includes a support including a support substrate, a piezoelectric layer with a thickness in a first direction and provided on a principal surface of the support, and a functional electrode on the principal surface of the piezoelectric layer. The piezoelectric layer includes first and second piezoelectric films that are laminated and each made of a single crystal of a same material. The first and second piezoelectric films have different polarization directions. The first and second piezoelectric films each include cleavage surfaces. At least one of the cleavage surfaces of the first piezoelectric film, and at least one of cleavage surfaces of the second piezoelectric film extend in intersecting directions in plan view in the first direction.