A refrigerator, comprising: an opening disposed at one side of a door; an ice bank disposed on a rear surface of the door, and configured to be drawn out through the opening, for storing ice pieces; a guide unit for guiding the ice bank to be drawn out; characterized by a volume control unit for changing a volume of the ice bank step by step, wherein the ice bank comprises: a body portion (110, 210, 310, 410) formed in a box shape having opened upper and lower surfaces; and a volume expansion container (120, 220, 320, 420) inserted into the body portion (110, 210, 310, 410) so as to be vertically moveable along an inner surface of the body portion, and forming an ice storage space having an opened upper surface, and wherein the volume control unit (130, 230, 330, 430) comprises: volume control grooves (131, 231, 331, 431) formed in a volume control direction of the ice bank, at one of inner side surfaces of the body portion and outer side surfaces of the volume expansion container; volume control protrusions (132, 232, 332, 432) formed at another of the inner side surfaces of the body portion and the outer side surfaces of the volume expansion container in correspondence to the volume control grooves (131, 231, 331, 431), the volume control protrusions (132, 232, 332, 432) being inserted into the volume control grooves (131, 231, 331, 431) to be movable in the volume control direction of the ice bank; and a locking unit (133, 134) (233, 234) (331, 332) (433, 434) for restricting a relative motion of the volume control grooves (131, 231, 331, 431) with respect to the volume control protrusions (132, 232, 332, 432) step by step. an opening disposed at one side of a door; an ice bank disposed on a rear surface of the door, and configured to be drawn out through the opening, for storing ice pieces; a guide unit for guiding the ice bank to be drawn out; characterized by a volume control unit for changing a volume of the ice bank step by step, a body portion (110, 210, 310, 410) formed in a box shape having opened upper and lower surfaces; and a volume expansion container (120, 220, 320, 420) inserted into the body portion (110, 210, 310, 410) so as to be vertically moveable along an inner surface of the body portion, and forming an ice storage space having an opened upper surface, and wherein the volume control unit (130, 230, 330, 430) comprises: volume control grooves (131, 231, 331, 431) formed in a volume control direction of the ice bank, at one of inner side surfaces of the body portion and outer side surfaces of the volume expansion container; volume control protrusions (132, 232, 332, 432) formed at another of the inner side surfaces of the body portion and the outer side surfaces of the volume expansion container in correspondence to the volume control grooves (131, 231, 331, 431), the volume control protrusions (132, 232, 332, 432) being inserted into the volume control grooves (131, 231, 331, 431) to be movable in the volume control direction of the ice bank; and a locking unit (133, 134) (233, 234) (331, 332) (433, 434) for restricting a relative motion of the volume control grooves (131, 231, 331, 431) with respect to the volume control protrusions (132, 232, 332, 432) step by step. volume control grooves (131, 231, 331, 431) formed in a volume control direction of the ice bank, at one of inner side surfaces of the body portion and outer side surfaces of the volume expansion container; volume control protrusions (132, 232, 332, 432) formed at another of the inner side surfaces of the body portion and the outer side surfaces of the volume expansion container in correspondence to the volume control grooves (131, 231, 331, 431), the volume control protrusions (132, 232, 332, 432) being inserted into the volume control grooves (131, 231, 331, 431) to be movable in the volume control direction of the ice bank; and a locking unit (133, 134) (233, 234) (331, 332) (433, 434) for restricting a relative motion of the volume control grooves (131, 231, 331, 431) with respect to the volume control protrusions (132, 232, 332, 432) step by step.