According to the present disclosure, a method for controlling a refrigerator includes operating a cooling device at a previously-determined output for cooling a storage space; measuring, by a temperature sensor, a temperature of the storage space in unit times; determining a representative temperature of the storage space based on the temperature measured by the temperature sensor, and determining whether the determined representative temperature of the storage space falls within a convergence temperature range, when an output change time is reached after the output of the cooling device is previously determined; maintaining the output of the cooling device or determining the output of the cooling device according to one of a plurality of methods including a first method and a second method when the representative temperature of the storage space falls within the convergence temperature range, and determining the output of the cooling device according to the second method when the representative temperature of the storage space is out of the convergence temperature range; and operating the cooling device at the determined output.