A cell stack management system includes a cell monitoring unit that measures an output voltage of a plurality of power storage cells, a battery management unit that manages a cell stack, and a first communication network that connects the cell monitoring unit and the battery management unit. The battery management unit includes: a first communication circuit connected to the first communication network; a second communication circuit connected to a second communication network for connecting to a higher-level system; a control circuit that controls the battery management unit; and a control circuit power supply. The cell stack management system includes a normal mode and a low-power mode as modes of operation. During transition from the low-power mode to the normal mode, the first communication circuit activates at least one of the control circuit power supply, the control circuit, or the second communication circuit.