A Coriolis flowmeter 10 vibrates a measurement tube through which a fluid subject to measurement flows, detects vibrations including Coriolis force developed in the fluid from the vibrations, and measures a mass flow rate of the fluid from a detection signal. The Coriolis flowmeter is characterized by including fluctuation calculation section 50 that calculates fluctuations from a detection signal SA; status value calculation section 60 that calculates a status value showing a state of air bubbles in the fluid from the fluctuations calculated by the fluctuation calculation section 50, and determination section 70 that determines a state of air bubbles from the status value calculated by the status value calculation section 60.