A heat pump water heater, comprising: a refrigerating cycle in which a compressor, a four-way valve that is configured to switch a flow direction of a refrigerant, a water heat exchanger that is configured to perform heat exchange between said refrigerant and water, an expansion mechanism that is configured to adjust a flow rate of the refrigerant and to decompress, and an air heat exchanger that is configured to perform heat exchange between the air and the refrigerant are sequentially and circularly connected by a pipeline; a water circuit in which said water heat exchanger, a hot water tank that reserves water heated by said water heat exchanger, and a pump are sequentially and circularly connected by a pipeline; a water channel pipeline that is a lower path of said air heat exchanger and being disposed in a lower stage of said air heat exchanger than a refrigerant pipeline of said air heat exchanger in which the refrigerant flows; a path switching valve disposed in the water circuit between said pump and said water heat exchanger; a bypass circuit connected between said path switching valve and an inlet of said water channel pipeline and connecting an outlet of said water channel pipeline to the water circuit between said path switching valve and an inlet of said water heat exchanger; characterized by a control portion that is configured to execute switching control of said four-way valve and said path switching valve, wherein said control portion is configured to switch, during defrosting operation of said air heat exchanger, a flow direction of the refrigerant in said refrigerating cycle by switching said four-way valve on the basis of predetermined information to supply the refrigerant discharged from said compressor to said refrigerant pipeline of said air heat exchanger, and switch said path switching valve to allow high-temperature water in said hot water tank to flow through the water channel pipeline of said air heat exchanger that is the lower path via said bypass circuit, to flow into said water heat exchanger, and to flow back to said hot water tank. a refrigerating cycle in which a compressor, a four-way valve that is configured to switch a flow direction of a refrigerant, a water heat exchanger that is configured to perform heat exchange between said refrigerant and water, an expansion mechanism that is configured to adjust a flow rate of the refrigerant and to decompress, and an air heat exchanger that is configured to perform heat exchange between the air and the refrigerant are sequentially and circularly connected by a pipeline; a water circuit in which said water heat exchanger, a hot water tank that reserves water heated by said water heat exchanger, and a pump are sequentially and circularly connected by a pipeline; a water channel pipeline that is a lower path of said air heat exchanger and being disposed in a lower stage of said air heat exchanger than a refrigerant pipeline of said air heat exchanger in which the refrigerant flows; a path switching valve disposed in the water circuit between said pump and said water heat exchanger; a bypass circuit connected between said path switching valve and an inlet of said water channel pipeline and connecting an outlet of said water channel pipeline to the water circuit between said path switching valve and an inlet of said water heat exchanger; characterized by a control portion that is configured to execute switching control of said four-way valve and said path switching valve, wherein said control portion is configured to switch, during defrosting operation of said air heat exchanger, a flow direction of the refrigerant in said refrigerating cycle by switching said four-way valve on the basis of predetermined information to supply the refrigerant discharged from said compressor to said refrigerant pipeline of said air heat exchanger, and switch said path switching valve to allow high-temperature water in said hot water tank to flow through the water channel pipeline of said air heat exchanger that is the lower path via said bypass circuit, to flow into said water heat exchanger, and to flow back to said hot water tank.