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 (233, 234), 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 (233, 234), 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.