An ice-making device for a refrigerator, comprising: a water tank for being detachably mounted to a rear surface of a refrigerator door; and an ice-making housing for being detachably mounted to the rear surface of the door below the water tank and provided with a predetermined installation space therein; wherein the ice-making housing comprises a first ice-making housing mounted below the water tank and having an ice tray installed in an installation space thereof, and a second ice-making housing mounted below the first ice-making housing and having an ice bank installed in an installation space thereof; wherein the ice tray is provided with an ice-making groove in which water supplied from the water tank is frozen into ice; and the ice bank for storing ice made in the ice tray, wherein the ice bank can be received in or withdrawn from the installation space; wherein support shafts are provided at both lateral sides of the ice tray to pivotally support the ice tray on the first ice-making housing, a stopper is provided on an inner side of the first ice-making housing and is located within a range of the ice tray pivoting about the support shafts, a pivoting lever is provided on an outer side of the first ice-making housing to allow the ice tray to be pivoted, and the ice made in the ice-making groove is separated from the ice-making groove and then stored in the ice bank by actuating the pivoting lever to allow the ice tray to be caught to the stopper and then twisted while the ice tray is pivoted; and wherein the ice-making device further comprises: a tray cover mounted in the installation space of the first ice-making housing to be vertically pivoted in cooperation with the pivot motion of the ice tray and to selectively open or close the ice-making groove; wherein the water tank is provided with a guide groove formed by depressing upward a portion of a bottom surface of the water tank, the first ice-making housing is provided with a guide rib protruding upward from the top surface of the ice-making housing, and the water tank can be guided by allowing the guide rib to be inserted and slid in the guide groove while the water tank is received in or withdrawn from the mounting space. a water tank for being detachably mounted to a rear surface of a refrigerator door; and an ice-making housing for being detachably mounted to the rear surface of the door below the water tank and provided with a predetermined installation space therein; wherein the ice-making housing comprises a first ice-making housing mounted below the water tank and having an ice tray installed in an installation space thereof, and a second ice-making housing mounted below the first ice-making housing and having an ice bank installed in an installation space thereof; wherein the ice tray is provided with an ice-making groove in which water supplied from the water tank is frozen into ice; and the ice bank for storing ice made in the ice tray, wherein the ice bank can be received in or withdrawn from the installation space; wherein support shafts are provided at both lateral sides of the ice tray to pivotally support the ice tray on the first ice-making housing, a stopper is provided on an inner side of the first ice-making housing and is located within a range of the ice tray pivoting about the support shafts, a pivoting lever is provided on an outer side of the first ice-making housing to allow the ice tray to be pivoted, and the ice made in the ice-making groove is separated from the ice-making groove and then stored in the ice bank by actuating the pivoting lever to allow the ice tray to be caught to the stopper and then twisted while the ice tray is pivoted; and wherein the ice-making device further comprises: a tray cover mounted in the installation space of the first ice-making housing to be vertically pivoted in cooperation with the pivot motion of the ice tray and to selectively open or close the ice-making groove; wherein the water tank is provided with a guide groove formed by depressing upward a portion of a bottom surface of the water tank, the first ice-making housing is provided with a guide rib protruding upward from the top surface of the ice-making housing, and the water tank can be guided by allowing the guide rib to be inserted and slid in the guide groove while the water tank is received in or withdrawn from the mounting space. a tray cover mounted in the installation space of the first ice-making housing to be vertically pivoted in cooperation with the pivot motion of the ice tray and to selectively open or close the ice-making groove; wherein the water tank is provided with a guide groove formed by depressing upward a portion of a bottom surface of the water tank, the first ice-making housing is provided with a guide rib protruding upward from the top surface of the ice-making housing, and the water tank can be guided by allowing the guide rib to be inserted and slid in the guide groove while the water tank is received in or withdrawn from the mounting space.