To realize a Coriolis mass flowmeter capable of generating stable vibration of a vibrating tube.

A Coriolis mass flowmeter measures a mass flow of measured fluid flowing through two vibrating tubes by using driving means composed of a coil and a magnet for vibrating the vibrating tubes in a mutually approaching and separating direction, and using two vibration sensors each composed of a coil and a magnet for detecting relative displacement of the vibrating tubes. The Coriolis mass flowmeter includes counterbalance means that vibrates in synchronization with the vibration of the tubes and counterbalances barycentric movement caused by flexure of the vibrating tubes.