A heat pump, comprising: a compressor; an outdoor heat exchanger that performs heat exchange between refrigerant and outdoor air; an indoor heat exchanger that performs heat exchange between refrigerant and indoor air; and an expander installed between the outdoor heat exchanger and the indoor heat exchanger, wherein the outdoor heat exchanger comprises: a refrigerant tube that guides refrigerant therethrough; a fin coupled to the refrigerant tube, wherein the fin is provided with a substantially cylindrical collar having an inner circumferential surface thereof in contact with the refrigerant tube and an outer circumferential surface thereof exposed to air flowing through the outdoor heat exchanger, and a plate body extended outside from the collar; a water repellent coating material applied to a first surface of the plate body of the fin; and a hydrophilic coating material applied to a second surface of the plate body of the fin, characterized in that the water repellent coating material is coated on the outer circumferential surface of the collar, the hydrophilic coating material is coated on the inner circumferential surface of the collar, and an area of the fin coated with the water repellent coating material is greater than 0.5 times and less than 0.6 times a total area thereof that is exposed to the air flowing through the outdoor heat exchanger. a compressor; an outdoor heat exchanger that performs heat exchange between refrigerant and outdoor air; an indoor heat exchanger that performs heat exchange between refrigerant and indoor air; and an expander installed between the outdoor heat exchanger and the indoor heat exchanger, wherein the outdoor heat exchanger comprises: a refrigerant tube that guides refrigerant therethrough; a fin coupled to the refrigerant tube, wherein the fin is provided with a substantially cylindrical collar having an inner circumferential surface thereof in contact with the refrigerant tube and an outer circumferential surface thereof exposed to air flowing through the outdoor heat exchanger, and a plate body extended outside from the collar; a water repellent coating material applied to a first surface of the plate body of the fin; and a hydrophilic coating material applied to a second surface of the plate body of the fin, characterized in that the water repellent coating material is coated on the outer circumferential surface of the collar, the hydrophilic coating material is coated on the inner circumferential surface of the collar, and an area of the fin coated with the water repellent coating material is greater than 0.5 times and less than 0.6 times a total area thereof that is exposed to the air flowing through the outdoor heat exchanger. a refrigerant tube that guides refrigerant therethrough; a fin coupled to the refrigerant tube, wherein the fin is provided with a substantially cylindrical collar having an inner circumferential surface thereof in contact with the refrigerant tube and an outer circumferential surface thereof exposed to air flowing through the outdoor heat exchanger, and a plate body extended outside from the collar; a water repellent coating material applied to a first surface of the plate body of the fin; and a hydrophilic coating material applied to a second surface of the plate body of the fin, characterized in that the water repellent coating material is coated on the outer circumferential surface of the collar, the hydrophilic coating material is coated on the inner circumferential surface of the collar, and an area of the fin coated with the water repellent coating material is greater than 0.5 times and less than 0.6 times a total area thereof that is exposed to the air flowing through the outdoor heat exchanger.