A method for controlling a constant temperature of a refrigerating compartment of a refrigerator which includes a compressor that supplies a compressed refrigerant, a refrigerating compartment evaporator that generates cold air for cooling the refrigerating compartment by receiving compressed refrigerant from the compressor, a freezing compartment evaporator that generates cold air for cooling a freezing compartment by receiving compressed refrigerant from the compressor, and a three way valve that selectively opens any one of a first passage connecting the compressor and the refrigerating compartment evaporator and a second passage connecting the compressor and the freezing compartment evaporator, a refrigerating fan for supplying the cold air generated by the refrigerating compartment evaporator to the refrigerating compartment, and a freezing fan for supplying the cold air generated by the freezing compartment evaporator to the freezing compartment, the method comprising: performing cooling for the refrigerating compartment and cooling for the freezing compartment so that a refrigerating compartment cooling operation for cooling the refrigerating compartment and a freezing compartment cooling operation for cooling the freezing compartment are alternately performed, wherein a time point at which the refrigerating compartment cooling operation and the freezing compartment cooling operation are alternated is dependent on a temperature of the refrigerating compartment, wherein the refrigerating compartment cooling operation includes at least any one of a first refrigerating compartment cooling operation that is performed in such a manner that the compressor and the refrigerating fan are operated and the three way valve opens the first passage, and a second refrigerating compartment cooling operation that is performed in such a manner that the refrigerating fan is operated in a state in which operation of the compressor is stopped and the three way valve opens the first passage, wherein one cooling cycle including at least one alternation of the refrigerating compartment cooling operation and the freezing compartment cooling operation is performed, and the refrigerating compartment cooling operation is performed at a last time point of the cooling cycle, and characterized in that the first refrigerating compartment cooling operation is performed at a last time point of the cooling cycle when an outside temperature around the refrigerating compartment exceeds a preset reference temperature, and the second refrigerating compartment cooling operation is performed when the outside temperature is less than or equal to the preset reference temperature. performing cooling for the refrigerating compartment and cooling for the freezing compartment so that a refrigerating compartment cooling operation for cooling the refrigerating compartment and a freezing compartment cooling operation for cooling the freezing compartment are alternately performed, wherein a time point at which the refrigerating compartment cooling operation and the freezing compartment cooling operation are alternated is dependent on a temperature of the refrigerating compartment, wherein the refrigerating compartment cooling operation includes at least any one of a first refrigerating compartment cooling operation that is performed in such a manner that the compressor and the refrigerating fan are operated and the three way valve opens the first passage, and a second refrigerating compartment cooling operation that is performed in such a manner that the refrigerating fan is operated in a state in which operation of the compressor is stopped and the three way valve opens the first passage, wherein one cooling cycle including at least one alternation of the refrigerating compartment cooling operation and the freezing compartment cooling operation is performed, and the refrigerating compartment cooling operation is performed at a last time point of the cooling cycle, and characterized in that the first refrigerating compartment cooling operation is performed at a last time point of the cooling cycle when an outside temperature around the refrigerating compartment exceeds a preset reference temperature, and the second refrigerating compartment cooling operation is performed when the outside temperature is less than or equal to the preset reference temperature.