a piezoelectric device includes idt electrodes and solves various problems resulting from the idt electrodes . the piezoelectric device has a configuration in which a piezoelectric thin - film and a support are bonded together such that the piezoelectric thin - film is supported by the support . idt electrodes and interconnect electrodes are provided on a surface of the piezoelectric thin - film that is located on the support side . the piezoelectric thin - film includes a region in which the idt electrodes are provided and on which no support is provided but an opening is formed . this allows the idt electrodes and the piezoelectric thin - film and the idt electrode - formed region of the piezoelectric thin - film to not be in contact with the support , thereby defining a membrane including only the piezoelectric thin - film and the idt electrodes as elements , the piezoelectric thin - film and the idt electrodes being disposed therein and being important for properties of the piezoelectric device .