To provide an ultrasonic flowmeter for preventing interference in reception signals and performing precise measurement, and to provide a method for measuring a flow rate.

The ultrasonic flowmeter 101 comprises first and second ultrasonic vibrators 1, 2 that transmit/receive ultrasonic waves and are arranged to form a propagation path of ultrasonic waves in a fluid channel; a transmission part 3 and a reception section 6 for driving the first and second ultrasonic vibrators 1, 2 for receiving ultrasonic waves so that ultrasonic waves can be transmitted and received bidirectionally between the first and the second ultrasonic vibrators 1, 2; and attenuation parts 14, 15 for readily attenuating vibration in the ultrasonic vibrator used for reception in the first and second ultrasonic vibrators 1, 2, thus detecting a bidirectional propagation time difference in ultrasonic waves propagated between propagation paths for measuring the flow rate of fluid.

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