The present invention discloses a defrost operating method for a refrigerator which performs a defrost operation by controlling operations of a compressor and a fan on the basis of a continuous operation time of the compressor and surface temperatures of evaporators to prevent frost from being formed on the evaporators, when cool air is generated in a freezing chamber and a refrigerating chamber by circulating refrigerants through a refrigeration cycle built in a refrigerator main body and forcibly circulated bX rotating the fan. The defrost operating method for the refrigerator can omit a general defrosting heater by performing the defrost operation by using the compressor and the fan. In addition, the defrost operating method for the refrigerator improves heat exchange efficiency and reduces power consumption by efficiently performing the defrost operation.