To provide a flowmeter capable of enhancing metering resolution to thus effect accurate metering. When a fluid to be measured is supplied to or discharged from a metering chamber 4, a membrane 11 provided in the metering chamber 4 is reciprocally actuated, and a rotation section R1 performs rotational movement in association with reciprocal movement of the membrane 11. At this time, since the rotation section R1 is provided with a magnet 5 or a direction sensor 6, the magnet 5 or the direction sensor 6 also effects rotational movement. The direction sensor 6 detects rotational movement, to thus determine a relative position between the membrane and the rotation section. Thus, the position of the membrane 11 can be detected, and metering resolution is enhanced. Thus, accurate metering can be performed.