CONSTANT FLOW CONTROL DEVICE

Object There is provided a constant flow control device at a small flow rate range that has the stability of the performance and a high reliability. Solution In a constant flow control device including a main elastic member 15 biasing a movable valve body 5 toward a direction in which the valve opens, a needle valve 13 is forward backward movably held at the movable valve body 5, the motion of the needle valve 13 in a direction toward a valve seat is limited at a predetermined position of the movable valve body 5, a throttle portion 11 is provided at the movable valve body 5, a needle valve elastic member 16 provided at the movable valve body 5 biases the needle valve 13 in the direction toward the valve seat and, when the differential pressure between a first chamber 6 and a second chamber 10 exceeds a predetermined differential pressure prescribed by the biasing force of the main elastic member 15, the movable valve body 5 can move up to a movable valve body receiving portion 17 included in a second housing 9 in the direction toward the valve seat while the needle valve 13 is closely contacted with and touches down on the valve seat such that the movable valve body receiving portion 17 receives a force of an excess in the differential pressure.