An air-conditioning apparatus comprising: a refrigerant circuit in which a compressor, a flow switching device, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger are connected by pipes, and through which refrigerant flows; and a control device configured to control an operation of the refrigerant circuit to perform switching between a heating operation and a defrosting operation, the control device including a determination unit configured to determine, based on operation information regarding the refrigerant circuit, during the heating operation, whether or not to change a requirement for starting the defrosting operation, a changing unit configured to change the requirement for starting the defrosting operation in accordance with a result of determination by the determination unit and determination of whether or not it is presumed that the heating operation is required, and a switching unit configured to cause, when the requirement for starting the defrosting operation is satisfied, the flow switching device to perform switching to start the defrosting operation wherein the air-conditioning apparatus further comprises: an outdoor heat-exchanger temperature detection device configured to detect a temperature of the outdoor heat exchanger, wherein the requirement for starting the defrosting operation is that the temperature detected by the outdoor heat-exchanger temperature detection device is at or below an outdoor heat-exchanger temperature threshold, and characterised in that the changing unit is configured to change, during the heating operation, the outdoor heat-exchanger temperature threshold to an outdoor heat-exchanger temperature relaxed threshold higher than the outdoor heat-exchanger temperature threshold in accordance with the operation information regarding the refrigerant circuit. a refrigerant circuit in which a compressor, a flow switching device, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger are connected by pipes, and through which refrigerant flows; and a control device configured to control an operation of the refrigerant circuit to perform switching between a heating operation and a defrosting operation, the control device including a determination unit configured to determine, based on operation information regarding the refrigerant circuit, during the heating operation, whether or not to change a requirement for starting the defrosting operation, a changing unit configured to change the requirement for starting the defrosting operation in accordance with a result of determination by the determination unit and determination of whether or not it is presumed that the heating operation is required, and a switching unit configured to cause, when the requirement for starting the defrosting operation is satisfied, the flow switching device to perform switching to start the defrosting operation a determination unit configured to determine, based on operation information regarding the refrigerant circuit, during the heating operation, whether or not to change a requirement for starting the defrosting operation, a changing unit configured to change the requirement for starting the defrosting operation in accordance with a result of determination by the determination unit and determination of whether or not it is presumed that the heating operation is required, and a switching unit configured to cause, when the requirement for starting the defrosting operation is satisfied, the flow switching device to perform switching to start the defrosting operation wherein the air-conditioning apparatus further comprises: an outdoor heat-exchanger temperature detection device configured to detect a temperature of the outdoor heat exchanger, wherein the requirement for starting the defrosting operation is that the temperature detected by the outdoor heat-exchanger temperature detection device is at or below an outdoor heat-exchanger temperature threshold, and characterised in that the changing unit is configured to change, during the heating operation, the outdoor heat-exchanger temperature threshold to an outdoor heat-exchanger temperature relaxed threshold higher than the outdoor heat-exchanger temperature threshold in accordance with the operation information regarding the refrigerant circuit. an outdoor heat-exchanger temperature detection device configured to detect a temperature of the outdoor heat exchanger, wherein the requirement for starting the defrosting operation is that the temperature detected by the outdoor heat-exchanger temperature detection device is at or below an outdoor heat-exchanger temperature threshold, and characterised in that the changing unit is configured to change, during the heating operation, the outdoor heat-exchanger temperature threshold to an outdoor heat-exchanger temperature relaxed threshold higher than the outdoor heat-exchanger temperature threshold in accordance with the operation information regarding the refrigerant circuit.