An air-conditioning apparatus comprising: at least one controller; an outdoor unit including a compressor, a first refrigerant flow path switching device, and a heat-source-side heat exchanger; a heat medium relay unit including an intermediate heat exchanger, an expansion device, a second refrigerant flow path switching device (18a, 18b), and a pump (21a, 21b); and at least one indoor unit including a use-side heat exchanger, wherein the compressor, the first refrigerant flow path switching device, the expansion device, the second refrigerant flow path switching device (18a, 18b), and the intermediate heat exchanger are connected using a refrigerant pipe, thereby making up a refrigeration cycle in which a refrigerant circulates, the intermediate heat exchanger and the use-side heat exchanger are connected using a heat medium pipe, thereby making up a heat medium circulation circuit in which a heat medium different from the refrigerant circulates, the controller is configured to switch the first refrigerant flow path switching device to execute a defrost operation mode in which a refrigerant discharged from the compressor is supplied to the heat-source-side heat exchanger, and characterized in that during the defrost operation mode, part of a refrigerant flowing out from the heat-source-side heat exchanger is supplied to the intermediate heat exchanger without passing through the expansion device, and rest of the refrigerant is returned to the outdoor unit without passing through the expansion device and the intermediate heat exchanger. at least one controller; an outdoor unit including a compressor, a first refrigerant flow path switching device, and a heat-source-side heat exchanger; a compressor, a first refrigerant flow path switching device, and a heat-source-side heat exchanger; a heat medium relay unit including an intermediate heat exchanger, an expansion device, a second refrigerant flow path switching device (18a, 18b), and a pump (21a, 21b); and an intermediate heat exchanger, an expansion device, a second refrigerant flow path switching device (18a, 18b), and a pump (21a, 21b); and at least one indoor unit including a use-side heat exchanger, wherein the compressor, the first refrigerant flow path switching device, the expansion device, the second refrigerant flow path switching device (18a, 18b), and the intermediate heat exchanger are connected using a refrigerant pipe, thereby making up a refrigeration cycle in which a refrigerant circulates, the intermediate heat exchanger and the use-side heat exchanger are connected using a heat medium pipe, thereby making up a heat medium circulation circuit in which a heat medium different from the refrigerant circulates, the controller is configured to switch the first refrigerant flow path switching device to execute a defrost operation mode in which a refrigerant discharged from the compressor is supplied to the heat-source-side heat exchanger, and characterized in that during the defrost operation mode, part of a refrigerant flowing out from the heat-source-side heat exchanger is supplied to the intermediate heat exchanger without passing through the expansion device, and rest of the refrigerant is returned to the outdoor unit without passing through the expansion device and the intermediate heat exchanger.