PURPOSE: To obtain a resonator with high sharpness and a filter with high sharpness by removing an etchable substance after a dielectric material whose one end surface is jointed to the surface of an etchable attachment and so on overlap and pile up and attach.

CONSTITUTION: The etchable substance 2 attaches to the surface of the substrate which is hardly etched by an appropriate area. The dielectric 3 whose one end surface is jointed, a metal 4 becoming a lower electrode, a piezoelectric body 5, a metal 6 as an upper electrode 8 and the substance 7 which is hardly etched attach to the substrate 1 and some part of the thin film 2. External electrodes 8 and 9 are connected to the ectrodes 4 and 6, respectively. Only the substance 2 is removed with an appropriate etching solution by etching, and an appropriate gap is provided between the substrate 1 and the substance 3. Such a cantilever eases distortion arising in the thin film formed on the substrate 1, whereby a piezoelectric thin film composite resonator employing a highly sharp elastic vibration and a filter can be available.