Piezoelectric oscillator

A piezoelectric oscillator comprising:

• a piezoelectric vibrating element that includes a piezoelectric strip, a first excitation electrode on a first surface of the piezoelectric strip, and a second excitation electrode on a second surface of the piezoelectric strip;
• a first crystal substrate having an external terminal and bonded to the first surface of the piezoelectric strip;
• and
• a second crystal substrate bonded to the second surface of the piezoelectric strip,
• wherein
• the first crystal substrate has a principal surface defined by a first basic axis and a second basic axis that intersects the first basic axis, and when an axis obtained by inclining, among mutually intersecting first axis, second axis, and third axis, which are crystallographic axes of crystal, the third axis around the first axis by a first predetermined angle is regarded as a first inclined axis, the first axis corresponds to the first basic axis and the first inclined axis corresponds to the second basic axis, and
• the first predetermined angle is any angle included in an angle range of −90 to −60 degrees and 80 to 90 degrees.