PURPOSE: To attain a enlarge a flow amount range, by dividing a detection chamber into a first and a second detection chambers by a condenser vibrating element and providing a condenser microphone to the detection chambers.

CONSTITUTION: A vibration detection chamber 3 is divided into a first and a second detection chambers 5, 6 and a condenser microphone 7 is provided between both detection chambers 5, 6. When a fluid to be measured flows through a fluid pipeline 1, vortexes are alternately generated left and right behind both side surfaces of a vortex generating column 2. At first, when the vortex is generated in the vicinity of a first pressure introducing port 8, the pressure in the side of the introducing port 8 is held to a low state as compared with that in the side of a second pressure introducing port 9 and pressures in the vicinity of both introducing ports 8, 9 are guided to the detection chambers 5, 6 through first and second conduits 10, 11 and pressure difference is generated between both detection chambers 5, 6 and a condenser vibrating element displaces to the side of the detection chamber 5 and condenser capacity becomes small. Next, then when vortex is generated in the side of the introducing port 9, the condenser vibrating element displaces to the side of the detection chamber 6 and the condenser capacity increases. By this method, the flow velocity of the fluid to be measured, that is, the number of generated vortexes are detected as the number of variations in the capacity of the condenser.