An ice making housing which is mounted in a refrigerator door and forms an ice making chamber including an ice making tray which has a rotational shaft to be rotatably accommodated in the ice making housing, and an ice generating unit to freeze supplied water; an ice separating unit which is mounted in the ice making housing and separates ice cubes from the ice making tray; an overflow preventing member which is rotatably coupled to the ice making housing along a lengthwise direction of the ice making tray and prevents overflow of water accommodated in the ice making tray; and a driving unit which is provided in the ice making tray and the overflow preventing member and allows the overflow preventing member to reciprocate between an ice separating position separating ice cubes from the ice generating unit and a cover position covering the ice generating unit.