A control system for a sodium-sulfur battery, which is composed of a plurality of battery modules connected in series, includes a control device having at least a temperature measuring unit for measuring a temperature of each battery module, a voltage measuring unit for measuring a voltage thereof, and a current measuring unit for measuring a current thereof assembled as a single control device. Preferably, the system includes a unit for detecting the end of discharge and the end of charge. Thus, the time lag in the detection of the end of discharge and the end of charge may be prevented. The reliability of a NaS battery during long-term operation is improved. A fluctuation in the power consumption of heaters during the driving of the NaS battery is reduced. The space required for installing power equipment such as a transformer may be omitted.