A reversible fuel cell includes a positive electrode containing manganese dioxide, a negative electrode containing a hydrogen storage material, a separator disposed between the positive electrode and the negative electrode, and an electrolyte. Each of the negative electrode and the positive electrode is an electrode for power generation and is also an electrode that applies electrolysis to the electrolyte using electric current to be fed from the outside. This cell is capable of storing electric energy to be supplied at the time of overcharge by converting the electric energy into gas, and is also capable of reconverting the gas into electric energy in order to utilize the electric energy. Accordingly, there are provided a reversible fuel cell and a reversible fuel cell system each of which is excellent in energy utilization efficiency, energy density and load following capability.