A flow verification system is adapted to verify flow characteristics just after a flow control device starts flow control by verifying a flow rate in a gas piping system which includes a first cutoff valve, the flow control device installed downstream from the first cutoff valve, and a pressure sensor for measuring pressure downstream from the flow control device, flow verification is made based on the pressure measured by the pressure sensor. The flow verification system also includes a benchmark storage device for storing a benchmark which is calculated by integrating the pressure values measured by the pressure sensor during a normal flow control operation, and an abnormality detection device for detecting an abnormal flow of process gas.