Abnormality Diagnosis Method of Fluid Supply Line

Provided is an abnormality diagnosis method of a fluid supply line including a plurality of fluid control devices F, V1, and V2 communicating with each other fluid-tightly. The abnormality diagnosis method has: a valve operation step of opening/closing any one or more of a valve FV in a flow rate control device, a valve V1, and a valve V2; a pressure adjustment step of setting a part or all of flow passages R1 and R2 leading from the valve V1 to the valve V2 via the flow rate control device to a vacuum state or a pressurization state; a pressure detection step of acquiring temporal pressure characteristics in a flow passage of the flow rate control device F by pressure detection mechanisms P1 and P2; and an abnormality determination step of comparing pressure characteristics at the time of abnormality diagnosis acquired by the pressure detection mechanisms P1 and P2 and pressure characteristics at the time of normality measured in advance under the same conditions, and determining whether or not there is an abnormality.