A refrigerator comprising: a cabinet having a storage compartment; a door provided at the cabinet; a water tank separably coupled to the door; an inlet port formed in the door to allow water, stored in the water tank, to be introduced into the door; characterized in that, the refrigerator further comprises: a support structure provided at the door to support the bottom of the water tank; a fixing rib protruded from the top of the water tank; a fixing unit provided at the rear surface of the door to fix the water tank, the fixing unit including: a first protrusion configured to be moved by elastic force and to be separably coupled to the fixing rib of the water tank, an elastic member configured to apply the elastic force to the first protrusion to fix the fixing rib of the water tank, a second protrusion connected to the first protrusion, and a connector configured to connect the first and the second protrusions (810, 820) to each other such that the first and the second protrusion (810, 820) are moved together; and a handle provided at the water tank to enable separation of the water tank from the fixing unit, the handle rotatably provided at the water tank, wherein the second protrusion is configured to come in contact with the handle and be moved upward and downward by the handle; wherein the water tank is separated from the fixing unit when the handle is rotated to contact and move the second protrusion such that the first protrusion is separated from the fixing rib. a cabinet having a storage compartment; a door provided at the cabinet; a water tank separably coupled to the door; an inlet port formed in the door to allow water, stored in the water tank, to be introduced into the door; characterized in that, the refrigerator further comprises: a support structure provided at the door to support the bottom of the water tank; a fixing rib protruded from the top of the water tank; a fixing unit provided at the rear surface of the door to fix the water tank, the fixing unit including: a first protrusion configured to be moved by elastic force and to be separably coupled to the fixing rib of the water tank, an elastic member configured to apply the elastic force to the first protrusion to fix the fixing rib of the water tank, a second protrusion connected to the first protrusion, and a connector configured to connect the first and the second protrusions (810, 820) to each other such that the first and the second protrusion (810, 820) are moved together; and a handle provided at the water tank to enable separation of the water tank from the fixing unit, the handle rotatably provided at the water tank, wherein the second protrusion is configured to come in contact with the handle and be moved upward and downward by the handle; wherein the water tank is separated from the fixing unit when the handle is rotated to contact and move the second protrusion such that the first protrusion is separated from the fixing rib. a support structure provided at the door to support the bottom of the water tank; a fixing rib protruded from the top of the water tank; a fixing unit provided at the rear surface of the door to fix the water tank, the fixing unit including: a first protrusion configured to be moved by elastic force and to be separably coupled to the fixing rib of the water tank, an elastic member configured to apply the elastic force to the first protrusion to fix the fixing rib of the water tank, a second protrusion connected to the first protrusion, and a connector configured to connect the first and the second protrusions (810, 820) to each other such that the first and the second protrusion (810, 820) are moved together; and a first protrusion configured to be moved by elastic force and to be separably coupled to the fixing rib of the water tank, an elastic member configured to apply the elastic force to the first protrusion to fix the fixing rib of the water tank, a second protrusion connected to the first protrusion, and a connector configured to connect the first and the second protrusions (810, 820) to each other such that the first and the second protrusion (810, 820) are moved together; and a handle provided at the water tank to enable separation of the water tank from the fixing unit, the handle rotatably provided at the water tank, wherein the second protrusion is configured to come in contact with the handle and be moved upward and downward by the handle; wherein the water tank is separated from the fixing unit when the handle is rotated to contact and move the second protrusion such that the first protrusion is separated from the fixing rib.