A refrigerator comprising: a main body including a storage space; a refrigerator door for selectively opening/closing the storage space; and an ice maker, the ice maker comprising a frame provided on a rear side of the refrigerator door; an ice tray rotatably installed in the frame, and having: a plurality of ice cube cavities; and a rotational shaft extending from a short side surface of the ice tray; a tray cover provided to the frame and selectively opening/closing the ice tray as the ice tray rotates; an elastic member provided between the frame and the tray cover; and water flood prevention ribs extending upward from upper edges of long side surfaces of the ice tray, and preventing water stored in the ice tray from flooding while the refrigerator door rotates, wherein a water flood prevention groove is provided to the tray cover, wherein the water flood prevention groove is formed by upwardly recessing a portion of a lower end of the tray cover, and wherein one of the water flood prevention ribs is selectively inserted in the water flood prevention groove, as the ice tray rotates, wherein an end of the tray cover is closely attached on an outer surface of the other one of the water flood prevention ribs by elastic force of the elastic member. a main body including a storage space; a refrigerator door for selectively opening/closing the storage space; and an ice maker, the ice maker comprising a frame provided on a rear side of the refrigerator door; an ice tray rotatably installed in the frame, and having: a plurality of ice cube cavities; and a rotational shaft extending from a short side surface of the ice tray; a tray cover provided to the frame and selectively opening/closing the ice tray as the ice tray rotates; an elastic member provided between the frame and the tray cover; and water flood prevention ribs extending upward from upper edges of long side surfaces of the ice tray, and preventing water stored in the ice tray from flooding while the refrigerator door rotates, wherein a water flood prevention groove is provided to the tray cover, wherein the water flood prevention groove is formed by upwardly recessing a portion of a lower end of the tray cover, and wherein one of the water flood prevention ribs is selectively inserted in the water flood prevention groove, as the ice tray rotates, wherein an end of the tray cover is closely attached on an outer surface of the other one of the water flood prevention ribs by elastic force of the elastic member. a frame provided on a rear side of the refrigerator door; an ice tray rotatably installed in the frame, and having: a plurality of ice cube cavities; and a rotational shaft extending from a short side surface of the ice tray; a plurality of ice cube cavities; and a rotational shaft extending from a short side surface of the ice tray; a tray cover provided to the frame and selectively opening/closing the ice tray as the ice tray rotates; an elastic member provided between the frame and the tray cover; and water flood prevention ribs extending upward from upper edges of long side surfaces of the ice tray, and preventing water stored in the ice tray from flooding while the refrigerator door rotates, wherein a water flood prevention groove is provided to the tray cover, wherein the water flood prevention groove is formed by upwardly recessing a portion of a lower end of the tray cover, and wherein one of the water flood prevention ribs is selectively inserted in the water flood prevention groove, as the ice tray rotates, wherein an end of the tray cover is closely attached on an outer surface of the other one of the water flood prevention ribs by elastic force of the elastic member.