To evaluate gas circulation equipment at a high pressure or high flow rate without separately preparing a power source.

A gas supply pipeline 1 having a high pressure pipeline 11 and a low pressure pipeline 13 connected to the high pressure pipeline 11 via a through a governor 120 is used, a connection pipe 20 to which gas flowing due to pressure difference between the high pressure pipeline 11 and low pressure pipeline 11 is supplied is disposed, and a reference flowmeter 22 and gas flowmeter 21 to be evaluated are inserted into the connection pipe 20 in series.