To provide a redox flow cell capable of preventing the mixture of a negative electrode electrolyte and a positive electrode electrolyte, and a fuel cell system using the same.

A redox flow cell 100 includes a first chamber 112 receiving a negative electrode electrolyte and having a first negative electrode 120 arranged, a second chamber 114 receiving hydrogen gas and having a first positive electrode 122 and a second negative electrode 124 arranged, a third chamber 116 receiving a positive electrode electrolyte and having a second positive electrode 126 arranged, an ion conductive first partition 130 for isolating the negative electrode electrolyte and the hydrogen gas, an ion conductive second partition 132 for isolating the positive electrode electrolyte and the hydrogen, and a conductor 134 for connecting the first positive electrode and the second negative electrode, and makes hydrogen generation reaction and hydrogen oxidation reaction by hydrogen gas intervene oxidation reduction reaction by the negative electrode electrolyte and the positive electrode electrolyte in charging and discharging. Thus, charging and discharging can be performed by preventing the mixture of the negative electrode electrolyte and the positive electrode electrolyte.