To provide a valve in which all the flow passages in contact with liquid can be filled with a sterilizing gas, and which can reliably discharge the sterilizing gas to the outside of a liquid feeding system, and also to provide the liquid feeding system including the valve.

A liquid feeding system 100 includes a medical solution bag 101, a constant flow rate valve 103, a pump 104, and flow passages 107, 108. The pump 104 includes a suction hole 141, a discharge hole 142, and check valves 143, 144. The constant flow rate valve 103 includes: a valve housing 110; a diaphragm 120 constituting a first valve chest 111 and a second valve chest 112 by dividing the inside of the valve housing 110; and a valve opening mechanism 150. A first opening 115, a second opening 117, and a third opening 118 are formed in the valve housing 110. The valve opening mechanism 150 includes: rubber 153; a pin 151 for pressurizing the diaphragm 120 from the second opening 117 to the second valve chest 112; and a handle member 152.