A heat pump boiler comprising: a compressor that is configured to compress a refrigerant; an exterior heat exchanger for exchanging heat between a flowing refrigerant and exterior air; an interior heat exchanger for exchanging heat between a flowing refrigerant and heating water; a channel change valve (14a, 14b, 14c) that is configured to send the refrigerant compressed by the compressor to the exterior heat exchanger or the interior heat exchanger; a first boiler heat exchanger for heating heating water that has passed through the interior heat exchanger, using combustion heat; a second boiler heat exchanger for exchanging heat between a flowing refrigerant and gas discharged from the first boiler heat exchanger; a defrosting valve that is configured to send a flowing refrigerant to the interior heat exchanger or the second boiler heat exchanger; an outdoor unit in which the compressor, the exterior heat exchanger, and the channel change valve (14a, 14b, 14c) are accommodated; an indoor unit in which the interior heat exchanger, the first boiler heat exchanger, and the second boiler heat exchanger are accommodated; a first refrigerant pipe forming a channel for a refrigerant that is discharged from the outdoor unit and supplied to the indoor unit; and a second refrigerant pipe forming a channel for a refrigerant that is discharged from the indoor unit and supplied to the outdoor unit; wherein the defrosting valve is configured to send a refrigerant supplied from the outdoor unit through the first refrigerant pipe to the interior heat exchanger or the second boiler heat exchanger, wherein the channel change valve (14a, 14b, 14c) includes: a first channel change valve that is configured to send a refrigerant discharged from the compressor to the interior heat exchanger via the first refrigerant pipe or the exterior heat exchanger; a second channel change valve that is configured to send a refrigerant discharged from the exterior heat exchanger to the compressor or the second boiler heat exchanger via the first refrigerant pipe; and a third channel change valve that is configured to send a refrigerant discharged from the interior heat exchanger to the exterior heat exchanger or to send a refrigerant discharged from the second boiler heat exchanger to the compressor. a compressor that is configured to compress a refrigerant; an exterior heat exchanger for exchanging heat between a flowing refrigerant and exterior air; an interior heat exchanger for exchanging heat between a flowing refrigerant and heating water; a channel change valve (14a, 14b, 14c) that is configured to send the refrigerant compressed by the compressor to the exterior heat exchanger or the interior heat exchanger; a first boiler heat exchanger for heating heating water that has passed through the interior heat exchanger, using combustion heat; a second boiler heat exchanger for exchanging heat between a flowing refrigerant and gas discharged from the first boiler heat exchanger; a defrosting valve that is configured to send a flowing refrigerant to the interior heat exchanger or the second boiler heat exchanger; an outdoor unit in which the compressor, the exterior heat exchanger, and the channel change valve (14a, 14b, 14c) are accommodated; an indoor unit in which the interior heat exchanger, the first boiler heat exchanger, and the second boiler heat exchanger are accommodated; a first refrigerant pipe forming a channel for a refrigerant that is discharged from the outdoor unit and supplied to the indoor unit; and a second refrigerant pipe forming a channel for a refrigerant that is discharged from the indoor unit and supplied to the outdoor unit; wherein the defrosting valve is configured to send a refrigerant supplied from the outdoor unit through the first refrigerant pipe to the interior heat exchanger or the second boiler heat exchanger, wherein the channel change valve (14a, 14b, 14c) includes: a first channel change valve that is configured to send a refrigerant discharged from the compressor to the interior heat exchanger via the first refrigerant pipe or the exterior heat exchanger; a second channel change valve that is configured to send a refrigerant discharged from the exterior heat exchanger to the compressor or the second boiler heat exchanger via the first refrigerant pipe; and a third channel change valve that is configured to send a refrigerant discharged from the interior heat exchanger to the exterior heat exchanger or to send a refrigerant discharged from the second boiler heat exchanger to the compressor. a first channel change valve that is configured to send a refrigerant discharged from the compressor to the interior heat exchanger via the first refrigerant pipe or the exterior heat exchanger; a second channel change valve that is configured to send a refrigerant discharged from the exterior heat exchanger to the compressor or the second boiler heat exchanger via the first refrigerant pipe; and a third channel change valve that is configured to send a refrigerant discharged from the interior heat exchanger to the exterior heat exchanger or to send a refrigerant discharged from the second boiler heat exchanger to the compressor.