To provide an ultrasonic vortex flowmeter capable of measuring a flowrate of a fluid to be measured by detecting a Karman vortex generated at a downstream side of a vortex generation unit by means of ultrasonic waves while judging the presence, absence or ratio of bubbles.

The vortex generation unit 16 is provided in a fluid channel 12 in which a fluid to be measured flows. When a drive signal is input to an ultrasonic transmitter 20 from a drive circuit 24, an ultrasonic wave transmitted from the ultrasonic transmitter 20 passes through the fluid to be measured to be received by an ultrasonic wave receiver 22. A signal of the Karman vortex 17 from a filter amplifier circuit 30 is input to a bubble detector 61 through an A/D converter 60. A bubble mixture amount computing section 47 always monitors whether or not an amplitude value of the A/D converted vortex signal exceeds a threshold (a correspondence value of a bubble mixture amount to a vortex frequency is stored beforehand in a memory section 44 by each aperture of a flowrate pipe). When it exceeds the threshold, a flowrate computing section 46 outputs a value which is obtained by subtracting the bubble mixture amount from a whole flowrate. Only the bubble mixture amount can be displayed.

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