An object is to provide a flow rate control device that can suppress a manufacturing cost and greatly reduce burdens of setting and maintenance.
A flow rate control device 11 of the invention is comprised with a flow rate adjusting valve 21 that is installed in a flow path 13, a flow rate measurement part 41 that measures a flow rate of a fluid flowing through the flow path 13, a controller 61 that controls opening degrees of the flow rate adjusting valve 21 based on a measurement result of the flow rate measurement part 41, and a pressure deficiency detecting function that detects pressure deficiency when a limit sensor 246 (an opening detecting sensor) that detects the opening of the flow rate adjusting valve 21 detects the opening degrees are full. With the structure, it becomes possible, compared with a conventional system to detect a pressure deficiency using a pressure sensor, to suppress a manufacturing cost and greatly reduce burdens of setting and maintenance and to notify of pressure deficiency at a necessary timing in an early stage before an abnormality occurs due to a flow rate decrease.