To provide a flow rate control valve that can improve responsiveness of flow rate control of a pressure differential type of a flow rate control device. The flow rate control valve is so configured to comprise a pair of valve members each of which has a seat surface being in contact with each other, to provide an internal flow channel that opens toward the seat surfaces and that passes through the inside of at least one of the valve members, and to control a flow rate of a fluid flowing out through the internal flow channel to the outside by adjusting a separation distance between the seat surfaces. And a restricted flow channel is formed in the internal flow channel so that a differential pressure is generated between an upstream side and a downstream side of the restricted flow channel.