To provide 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 12 that is connected to a flow rate control device 10 and to which gas is input, a second cutoff valve 13 for discharging the gas, a communication member 18 for allowing the first cutoff valve 12 and the second cutoff valve 13 to communicate with each other, a pressure sensor 14 for detecting the pressure of the gas supplied between the first cutoff valve 12 and the second cutoff valve 13, a temperature detector 15 for detecting the temperature of the gas supplied between the first cutoff valve 12 and the second cutoff valve 13, and a control means 16 for verifying the flow of the gas flowing in the flow control device 10, the verification being performed by using both the result of the pressure detected by the pressure sensor 14 and the result of the temperatures detected by the temperature detector 15. The volume Vk between the valve seat 22 of the first cutoff valve 12 and the valve seat 28 of the second cutoff valve 13 is equal to or less than the volume Ve between the outlet of the flow control device 10 and the valve seat 22 of the first cutoff valve 12.