A redox flow battery system includes pumps, a pump control unit, an SQC measuring unit, and a terminal-voltage measuring unit. The pump control unit includes a reference-flow-rate acquiring unit which acquires a reference flow rate of the pumps corresponding to the state of charge of electrolytes; a terminal-voltage determination unit which determines whether or not a terminal voltage of a battery cell reaches the lower limit or the ripper limit of a predetermined voltage range; and a pump-flow-rate setting unit which sets the reference flow rate for the pumps in the case where the terminal voltage does not reach the upper or lower limit of the predetermined voltage range, and sets a flow rate obtained by adding a predetermined flow rate to the reference flow rate for the pumps in the ease where the terminal voltage reaches the upper or lower limit of the predetermined voltage range.