Gas flow meter

The invention provides a gas flow meter provided with: a device main body (1) for gas-tight containment of a fluid under measurement; an inlet pipe for inflow of the fluid under measurement into the device main body (1); and an outlet pipe (5) for outflow of the fluid under measurement from the device main body (1). Also provided are: an ultrasonic flow rate measurement unit (9) connected to the outlet pipe (5), for measuring the flow rate of the fluid under measurement flowing through the interior; a connecting pipe (7) connected to the outlet pipe (5); and a flow passage member (10) connected to the connecting pipe (7) and identical in shape to the flow passage shape of the ultrasonic flow rate measurement unit (9). A support member (11) is provided for fastening the ultrasonic flow rate measurement unit (9) and the flow passage member (10). In so doing, the gas flow meter capable of consistent flow rate measurement can be achieved.