An air-conditioning apparatus comprising: an intermediate heat exchanger including a first heat transfer unit in which refrigerant flows, and a second heat transfer unit in which a heat medium different from the refrigerant flows, the intermediate heat exchanger being configured to exchange heat between the first heat transfer unit and the second heat transfer unit; a refrigerant cycle circuit including a heat source-side heat exchanger, the heat source-side heat exchanger being connected with the first heat transfer unit by a pipe, the refrigerant cycle circuit being configured to allow the refrigerant to circulate inside the refrigerant cycle circuit; a heat-medium cycle circuit including a use-side heat exchanger, the use-side heat exchanger being connected with the second heat transfer unit by a pipe (121, 122, 123a, 125, 126, 127a), the heat-medium cycle circuit being configured to allow the heat medium to circulate inside the heat-medium cycle circuit; and a discharge mechanism provided at the heat-medium cycle circuit and including a discharge valve, the discharge mechanism being configured to, when the discharge valve is open, discharge air present inside the heat-medium cycle circuit to an outside of the heat-medium cycle circuit, characterised in that the air-conditioning apparatus comprises a controller comprising a control unit which is configured to execute an air discharge operation mode in which the air present inside the heat-medium cycle circuit is discharged to the outside of the heat-medium cycle circuit, the air discharge operation mode including a first operation mode, and a second operation mode performed after the first operation mode, wherein the first operation mode is an operation mode in which, with the heat source-side heat exchanger functioning as a radiator, and with the first heat transfer unit functioning as an evaporator, the refrigerant circulates in the refrigerant cycle circuit, and with the discharge valve of the discharge mechanism being closed, the heat medium circulates in the heat-medium cycle circuit, and wherein the second operation mode is an operation mode in which, with the heat source-side heat exchanger functioning as an evaporator, and with the first heat transfer unit functioning as a radiator, the refrigerant circulates in the refrigerant cycle circuit, and with the discharge valve of the discharge mechanism being open, the heat medium circulates in the heat-medium cycle circuit. an intermediate heat exchanger including a first heat transfer unit in which refrigerant flows, and a second heat transfer unit in which a heat medium different from the refrigerant flows, the intermediate heat exchanger being configured to exchange heat between the first heat transfer unit and the second heat transfer unit; a refrigerant cycle circuit including a heat source-side heat exchanger, the heat source-side heat exchanger being connected with the first heat transfer unit by a pipe, the refrigerant cycle circuit being configured to allow the refrigerant to circulate inside the refrigerant cycle circuit; a heat-medium cycle circuit including a use-side heat exchanger, the use-side heat exchanger being connected with the second heat transfer unit by a pipe (121, 122, 123a, 125, 126, 127a), the heat-medium cycle circuit being configured to allow the heat medium to circulate inside the heat-medium cycle circuit; and a discharge mechanism provided at the heat-medium cycle circuit and including a discharge valve, the discharge mechanism being configured to, when the discharge valve is open, discharge air present inside the heat-medium cycle circuit to an outside of the heat-medium cycle circuit, characterised in that the air-conditioning apparatus comprises a controller comprising a control unit which is configured to execute an air discharge operation mode in which the air present inside the heat-medium cycle circuit is discharged to the outside of the heat-medium cycle circuit, the air discharge operation mode including a first operation mode, and a second operation mode performed after the first operation mode, wherein the first operation mode is an operation mode in which, with the heat source-side heat exchanger functioning as a radiator, and with the first heat transfer unit functioning as an evaporator, the refrigerant circulates in the refrigerant cycle circuit, and with the discharge valve of the discharge mechanism being closed, the heat medium circulates in the heat-medium cycle circuit, and wherein the second operation mode is an operation mode in which, with the heat source-side heat exchanger functioning as an evaporator, and with the first heat transfer unit functioning as a radiator, the refrigerant circulates in the refrigerant cycle circuit, and with the discharge valve of the discharge mechanism being open, the heat medium circulates in the heat-medium cycle circuit.