Disclosed herein is stack-type flow energy storage system. More particularly, the system includes a stack-type electrode cell composed of fluidic electrode material mixed with an electrolyte and storage tank for the electrode material, thereby remarkably improving stability, output and energy density. The stack-type flow energy storage system is advantageous in that unit cells, each consisting of a cathode, a separation membrane and an anode, are connected in parallel or in series to each other to make a stack cell, thus remarkably increasing output power. Further, the stack-type flow energy storage system is advantageous in that the sizes of slurry storage tanks connected to an electrode cell are adjusted, thus determining the required specification of energy density.