CELL STACK AND REDOX FLOW BATTERY

A cell stack including; a stacked body including a plurality of cell frames each having a bipolar plate whose outer periphery is supported by a frame member; and a pair of end plates that tighten the stacked body from both sides of a stacking direction thereof, wherein an area S [cm] of each cell frame as viewed from the stacking direction of the stacked body and a length W [mm] in the stacking direction of the stacked body satisfies a relationship 0.05≤W/S≤0.9.