The invention is applicable to air tightness detection of piezoelectric elements, and provides a detection device for the air tightness of a piezoelectric element. The detection device comprises a frequency generator, a signal detection device, a plurality of switches and an air tightest test chamber, wherein the frequency generator is connected with the signal detection device via a conducting wire to form a detection circuit, one end of each switch is connected with the conducting wire, the other end of the switch is connected with a piezoelectric element to be detected, the piezoelectric element to be detected is placed in the air tightest test chamber, one end of the piezoelectric element to be detected is connected with the switch, the other end of the piezoelectric element to be detected is connected with a ground wire, and the signal detection device is used for detecting the voltage and the phase difference of the detection circuit. During air tightness detection of a large batch of piezoelectric elements, whether the air tightness of the piezoelectric elements is good can be judged only by acquiring data changes of the piezoelectric elements under different pressure and ahead and behind resonance points, without visual inspection, an external oscillating circuit and the like, so the detection method is simple and fast in detection.