A method for manufacturing a piezoelectric oscillator includes the steps of: forming a first semiconductor layer above a substrate; forming a second semiconductor layer above the first semiconductor layer; forming a first opening section that exposes the substrate by removing the second semiconductor layer and the first semiconductor layer in an area for forming a support section; forming the support section in the first opening section; forming a driving section that generates flexing vibration in an oscillation section above the second semiconductor layer; patterning the second semiconductor layer to form the oscillation section having the supporting section as a base end and another end provided so as not to contact the supporting section, and a second opening section that exposes the first semiconductor layer; and removing the first semiconductor layer through a portion exposed at the second opening section by an etching method, thereby forming a cavity section at least below the oscillation section, wherein the step of forming the driving section includes the steps of forming a first electrode, forming a piezoelectric layer above the first electrode, and forming a second electrode above the piezoelectric layer.