A refrigerator comprising: an inner case configured to define a storage space ; a cool air duct configured to guide a flow of air within the storage space , the cool air duct being configured to define a heat exchange space together with the inner case ; an evaporator disposed in the heat exchange space between the inner case and the cool air duct ; a bypass passage disposed to be recessed in the cool air duct , the bypass passage being configured so that the air flows to bypass the evaporator ; a sensor disposed in the bypass passage , the sensor having an output value varying according to a flow rate of the air flowing through the bypass passage ; a defroster configured to remove frost generated on a surface of the evaporator ; and a controller configured to control the defroster based on the output value of the sensor ; wherein the refrigerator further comprises a passage cover configured to cover the bypass passage so as to partition the bypass passage from the heat exchange space , wherein the cool air duct comprises a bottom wall and both sidewalls , which define the bypass passage , characterized in that the passage cover comprises a cover plate configured to cover the bypass passage in a state of being spaced apart from the bottom wall , and the sensor is disposed to be spaced apart from the bottom wall and the cover plate in the bypass passage , wherein the cool air duct comprises a vertical extension surface that is a surface in which the bypass passage is defined, and the passage cover further comprises a barrier extending from the cover plate , the barrier protruding downward from the vertical extension surface in a state in which the cover plate covers the bypass passage . an inner case configured to define a storage space ; a cool air duct configured to guide a flow of air within the storage space , the cool air duct being configured to define a heat exchange space together with the inner case ; an evaporator disposed in the heat exchange space between the inner case and the cool air duct ; a bypass passage disposed to be recessed in the cool air duct , the bypass passage being configured so that the air flows to bypass the evaporator ; a sensor disposed in the bypass passage , the sensor having an output value varying according to a flow rate of the air flowing through the bypass passage ; a defroster configured to remove frost generated on a surface of the evaporator ; and a controller configured to control the defroster based on the output value of the sensor ; wherein the refrigerator further comprises a passage cover configured to cover the bypass passage so as to partition the bypass passage from the heat exchange space , wherein the cool air duct comprises a bottom wall and both sidewalls , which define the bypass passage , characterized in that the passage cover comprises a cover plate configured to cover the bypass passage in a state of being spaced apart from the bottom wall , and the sensor is disposed to be spaced apart from the bottom wall and the cover plate in the bypass passage , wherein the cool air duct comprises a vertical extension surface that is a surface in which the bypass passage is defined, and the passage cover further comprises a barrier extending from the cover plate , the barrier protruding downward from the vertical extension surface in a state in which the cover plate covers the bypass passage . <EOS>