A gas flow rate verification unit capable of enhancing reliability of gas flow rate verification. The gas flow rate verification unit has a first cutoff valve that is connected to a flow rate control device and to which gas is inputted, a second cutoff valve for discharging the gas, a communication member for allowing the first cutoff valve and the second cutoff valve to communicate with each other, a pressure sensor for detecting the pressure of the gas supplied between the first cutoff valve and the second cutoff valve, a temperature detector for detecting the temperature of the gas supplied between the first cutoff valve and the second cutoff valve, and a control means for verifying the flow of the gas flowing in the flow control device, the verification being performed by using both the result of the pressure detected by the pressure sensor and the result of the temperatures detected by the temperature detector. The volume (Vk) between the valve seat of the first cutoff valve and the valve seat of the second cutoff valve is equal to or less than the volume (Ve) between the outlet of the flow control device and the valve seat of the first cutoff valve.