Pipeline management system and control method thereof

To obtain a pipeline management system that appropriately controls the returning state of return gas from a gas separation system (4) to a gas grid, prevents deterioration of the gas grid and a gas separation system, and reduces uneven distribution of gas concentration in the gas grid, the present invention is characterized by comprising: a gas separation system that is connected to a gas pipeline (1), that draws a gas out from the gas pipeline which is filled with the gas, and that returns the gas to the gas pipeline; and a pipeline management device that receives input of at least fluid information for the gas pipeline, the pipeline management device determining whether or not the gas can be returned to the gas pipeline from a flow velocity ratio of the gas pipeline and a return gas (104), and the pipeline management device enabling gas return if the flow velocity ratio of the gas is within a predetermined range, and disabling gas return when the flow velocity ratio falls below the predetermined range or exceeds the predetermined range.