A method of controlling a refrigerator includes starting a first cooling cycle to cool a first storage compartment by operating a compressor and a first fan, determining whether a start condition of a second cooling cycle to cool a second storage compartment is satisfied, operating a second fan for the second storage compartment when the start condition of the second cooling cycle is satisfied, determining whether an output change condition of the second fan is satisfied while the second fan operates, and changing a speed of the second fan when the output change condition of the second fan is satisfied.