In a method for controlling a sodium-sulfur battery, a time of correcting or resetting a depth of discharge of the sodium-sulfur battery is determined within a predetermined period based on weather information, and the depth of discharge of the sodium-sulfur battery is corrected or reset in the determined time. According to this sodium-sulfur battery control method, the depth of discharge of the sodium-sulfur battery can be accurately managed in a small-scale interconnected system.