An air-conditioning apparatus comprising: an outdoor unit (2a, 2b); and an indoor unit (8a to 8e), wherein the indoor unit (8a to 8e) includes a refrigerant temperature sensor configured to detect a temperature of a refrigerant that is dischargeable out of an indoor heat exchanger (81a to 81e), wherein the outdoor unit (2a, 2b) comprising: an outdoor heat exchanger (24a, 24b, 25a, 25b); a compressor (21a, 21b); a refrigerant pipe configured to couple the outdoor heat exchanger (24a, 24b, 25a, 25b) and the compressor (21a, 21b) with the indoor unit (8a to 8e) including the indoor heat exchanger (81a to 81e); and a control unit configured to determine whether the heating capacity of the indoor unit (8a to 8e) performing a heating operation is lowered by the stagnation of the refrigerant in the indoor heat exchanger (81a to 81e), and wherein the control unit is configured to perform refrigerant stagnation elimination control for causing the refrigerant stagnated in the indoor heat exchanger (81a to 81e) of the indoor unit (8a to 8e) to flow out from the indoor heat exchanger (81a to 81e) when determining that the heating capacity of the indoor unit (8a to 8e) performing the heating operation is lowered by the stagnation of the refrigerant in the indoor heat exchanger (81a to 81e), wherein the outdoor unit (2a, 2b) further comprises a high-pressure sensor (50a, 50b) configured to detect the pressure of the refrigerant that flows from the compressor (21a, 21b) to the indoor heat exchanger (81a to 81e), wherein the control unit calculates a high-pressure saturation temperature based on the pressure detected by the high-pressure sensor (50a, 50b), and the control unit performs the refrigerant stagnation elimination control upon determining the follows: a first temperature difference between the high-pressure saturation temperature and an indoor unit (8a to 8e) side refrigerant temperature that is the temperature of the refrigerant discharged out of the indoor heat exchanger (81a to 81e) is not less than a predetermined value; characterised in that the control unit performs the refrigerant stagnation elimination control upon further determining the follows: the high-pressure saturation temperature is not less than a first predetermined temperature; and the indoor unit (8a to 8e) side refrigerant temperature is not more than a second predetermined temperature. an outdoor unit (2a, 2b); and an indoor unit (8a to 8e), wherein the indoor unit (8a to 8e) includes a refrigerant temperature sensor configured to detect a temperature of a refrigerant that is dischargeable out of an indoor heat exchanger (81a to 81e), wherein the an outdoor heat exchanger (24a, 24b, 25a, 25b); a compressor (21a, 21b); a refrigerant pipe configured to couple the outdoor heat exchanger (24a, 24b, 25a, 25b) and the compressor (21a, 21b) with the indoor unit (8a to 8e) including the indoor heat exchanger (81a to 81e); and a control unit configured to determine whether the heating capacity of the indoor unit (8a to 8e) performing a heating operation is lowered by the stagnation of the refrigerant in the indoor heat exchanger (81a to 81e), and wherein the control unit is configured to perform refrigerant stagnation elimination control for causing the refrigerant stagnated in the indoor heat exchanger (81a to 81e) of the indoor unit (8a to 8e) to flow out from the indoor heat exchanger (81a to 81e) when determining that the heating capacity of the indoor unit (8a to 8e) performing the heating operation is lowered by the stagnation of the refrigerant in the indoor heat exchanger (81a to 81e), wherein the outdoor unit (2a, 2b) further comprises the control unit calculates a high-pressure saturation temperature based on the pressure detected by the high-pressure sensor (50a, 50b), and the control unit performs the refrigerant stagnation elimination control upon determining the follows: a first temperature difference between the high-pressure saturation temperature and an indoor unit (8a to 8e) side refrigerant temperature that is the temperature of the refrigerant discharged out of the indoor heat exchanger (81a to 81e) is not less than a predetermined value; characterised in that the control unit performs the refrigerant stagnation elimination control upon further determining the follows: the high-pressure saturation temperature is not less than a first predetermined temperature; and the indoor unit (8a to 8e) side refrigerant temperature is not more than a second predetermined temperature. a first temperature difference between the high-pressure saturation temperature and an indoor unit (8a to 8e) side refrigerant temperature that is the temperature of the refrigerant discharged out of the indoor heat exchanger (81a to 81e) is not less than a predetermined value; characterised in that the control unit performs the refrigerant stagnation elimination control upon further determining the follows: the high-pressure saturation temperature is not less than a first predetermined temperature; and the indoor unit (8a to 8e) side refrigerant temperature is not more than a second predetermined temperature. the high-pressure saturation temperature is not less than a first predetermined temperature; and the indoor unit (8a to 8e) side refrigerant temperature is not more than a second predetermined temperature.