To provide a flow rate official approval apparatus for diagnosing failure capable of improving reliability of flow rate official approval.

The flow rate official approval apparatus 8 for diagnosing failure includes a failure diagnosing means 21 provided with a mode diagnosing failure of a flow rate measuring means 12 when detecting flow rate abnormality with a flow rate official unit 10 by being used in a gas feed piping system 25 provided with a plurality of pieces of flow rate control equipment 4A, 4B, 4C and the flow rate official approval unit 10 for detecting flow rate abnormality by measuring flow rates of each flow rate control equipment 4A, 4B, 4C... based on pressure measured with a pressure measuring means 12.