PURPOSE: To maintain a pump in s resonance state and to improve the efficiency of the pump by a method wherein a ratio between a voltage applied on a piezoelectric vibrator and the natural frequency of fluid fed with a pressure through vibration of the piezoelectric vibrator is set to a value being within a specified range.

CONSTITUTION: In a vibrator pump 1, by vibrating a plurality of piezoelectric vibrators 2 and 2', supported by a plurality of support bodies 5 and 5', by applying each voltage, fluid is sucked through a check valve 4 on the suction side by means of a suction pipe 7, and thereafter the fluid is delivered through a delivery pipe 6 by means of a check valve 3 on the delivery side. In this case, a ratio (fa/fb) of 8 frequency (fa) of a voltage applied on each of the piezoelectric vibrators 2 and 2' to a natural frequency (fb) of fluid is specified to a value within a range of 0.70-2.50. This constitution maintains the pump in a resonance state and improves the efficiency of the pump.