PURPOSE: To save the power consumption of the flowmeter by a method wherein a piezoelectric element is used as a vibration generation means, a mesuring tube is former as a straight tube, the strain direction of the piezoelectric element is set in the lengthwise direction of the measuring tube and both-end action parts of the piezoelectric element are attached to parts corresponding to sides of vibrations of the measuring tube.

CONSTITUTION: Both ends of a measuring tube 11 are supported by housings 12, 13, and laminated ceramic actuators 14, 15 as piezoelectric elements acting as vibration generation means for the measuring tube 11 are attached to the upper and lower side faces in its central part (parts corresponding to sides of vibrations). At this time, e.g. fixing members whose cross section is L-shaped are fixed to the tube 11 so as to be faced, and the actuators 14, 15 are fixed to them. When a voltage is applies in such a way that strains of the actuators 14, 15 are opposite to each other, the fixing member at the lower part is contracted when the fixing member fixing at the upper part is expanded, and the measuring tube 11 is bent upward. In addition, when an impressed voltage is reversed, the measuring tube is bent downward. In this manner, when the fixing members are expanded and contracted alternately at the resonance frequency of the measuring tube 11, vibrations are generated, Coriolis' force is generated in a fluid flowing in the measuring tube 11 and the phase of the vibrations is deformed. When the phase is detected by a speed sensor or the like, the mass flow rate of the fluid can be measured at small electric power.