A method for controlling a refrigerator including: determining whether a defrosting period for a freezing chamber and a deep freezing chamber has elapsed; when it is determined that the defrosting period has elapsed, performing a deep cooling operation for bringing at least one among the temperature of the deep freezing chamber and temperature of the freezing chamber down to a temperature lower than a control temperature; and defrosting the deep freezing chamber when the deep cooling operation is terminated. When the defrosting of the deep freezing chamber is started, a freezing chamber valve is closed to block cold air flow. The defrosting of the deep freezing chamber includes cold sink defrosting and heat sink defrosting performed after the cold sink defrosting is completed, and while the heat sink defrosting is being performed, a deep freezing chamber fan is driven to remove vapor generated during the cold sink defrosting.