A method for controlling a refrigerator, wherein the refrigerator comprises: a refrigerating compartment; a freezing compartment partitioned from the refrigerating compartment; a deep freezing compartment accommodated in the freezing compartment and partitioned from the freezing compartment; a thermoelectric module provided to cool the deep freezing compartment to a temperature lower than that of the freezing compartment; a temperature sensor configured to detect a temperature within the deep freezing compartment; a deep freezing compartment fan configured to allow internal air of the deep freezing compartment to forcibly flow; and a controller configured to control driving of the thermoelectric module and the deep freezing compartment fan; the method comprising: wherein, when a deep freezing compartment mode is in on state, any one of a low voltage, a medium voltage, a high voltage, and a reverse voltage is applied to the thermoelectric module according to an operation mode of the refrigerator, and when it is determined that the temperature of the deep freezing compartment is in a satisfactory temperature region, the controller is configured to apply the low voltage to the thermoelectric module, wherein, when a freezing compartment defrost operation starts, the reverse voltage is applied to the thermoelectric module of the deep freezing compartment to perform the freezing compartment defrost operation and a deep freezing compartment defrost operation at the same time. a refrigerating compartment; a freezing compartment partitioned from the refrigerating compartment; a deep freezing compartment accommodated in the freezing compartment and partitioned from the freezing compartment; a thermoelectric module provided to cool the deep freezing compartment to a temperature lower than that of the freezing compartment; a temperature sensor configured to detect a temperature within the deep freezing compartment; a deep freezing compartment fan configured to allow internal air of the deep freezing compartment to forcibly flow; and a controller configured to control driving of the thermoelectric module and the deep freezing compartment fan; the method comprising: wherein, when a deep freezing compartment mode is in on state, any one of a low voltage, a medium voltage, a high voltage, and a reverse voltage is applied to the thermoelectric module according to an operation mode of the refrigerator, and when it is determined that the temperature of the deep freezing compartment is in a satisfactory temperature region, the controller is configured to apply the low voltage to the thermoelectric module, wherein, when a freezing compartment defrost operation starts, the reverse voltage is applied to the thermoelectric module of the deep freezing compartment to perform the freezing compartment defrost operation and a deep freezing compartment defrost operation at the same time. wherein, when a deep freezing compartment mode is in on state, any one of a low voltage, a medium voltage, a high voltage, and a reverse voltage is applied to the thermoelectric module according to an operation mode of the refrigerator, and when it is determined that the temperature of the deep freezing compartment is in a satisfactory temperature region, the controller is configured to apply the low voltage to the thermoelectric module, wherein, when a freezing compartment defrost operation starts, the reverse voltage is applied to the thermoelectric module of the deep freezing compartment to perform the freezing compartment defrost operation and a deep freezing compartment defrost operation at the same time.