A flow battery apparatus is provided with shunted currents repressed. The apparatus has a positive electrode device, a negative electrode device and a plurality of gas-gap devices. Gas-gap devices are separately set between branching channels and inlet and outlet manifolds of positive and negative electrodes. Each of the branching channels separately has an inserting tube to be inserted into one of the gas-gap devices. The diameter of the inserted vessel of gas-gap devices is bigger than the diameter of the inserting tube connected to a corresponding one of the branching channels. Thus, working liquids transferred to the positive and negative electrodes are segregated with coordination of the gas-gap devices. Only air spaces and discrete liquid drops are left between separated parts of the working liquids. Thus, shunted currents are repressed by preventing conductive paths from being formed between the positive and negative electrodes.