An air-conditioning apparatus comprising: a refrigerant circuit in which a compressor, a heat-source-side heat exchanger, a plurality of expansion devices, refrigerant-side flows of a plurality of intermediate heat exchangers, and a plurality of refrigerant flow switching devices that perform switching of circulation paths are connected with refrigerant pipes, through which a heat-source-side refrigerant circulates pressure sensors that detect the pressure of the heat-source side refrigerant in the refrigerant pipes; a heat medium circuit in which pumps, a plurality of use-side heat exchangers, heat medium flow control devices, and heat-medium-side flows of the intermediate heat exchangers are connected with heat medium pipes, through which a heat medium circulates; and a controller that controls an opening degree of at least one of the heat medium flow control devices to adjust a flow rate of the heat medium, wherein, the controller performs a pressure variation suppressing operation for suppressing a refrigerant pressure variation on a side of the refrigerant circuit by controlling the at least one of the heat medium flow control devices to have a first opening degree so as to allow a certain amount of heat medium to flow through at least one of the use-side heat exchangers of the plurality of the use-side heat exchangers, before the at least one of the use-side heat exchangers of the plurality of the use-side heat exchangers starts operation or performs switching of an operation mode; and characterized in that the controller, after controlling the at least one heat medium flow control devices to have the first opening degree, compares a preset predetermined pressure with a pressure difference between a pressure of the heat-source side refrigerant before the at least one of the heat medium flow control devices is set to have the first opening degree and a pressure of the heat-source side refrigerant after the at least one of the heat medium flow control devices is set to have the first opening degree, and when the pressure difference is smaller than the predetermined pressure, the controller controls the at least one of the heat medium flow control devices whose opening degree has been controlled to the first opening degree to have a second opening degree that is greater than the first opening degree. a refrigerant circuit in which a compressor, a heat-source-side heat exchanger, a plurality of expansion devices, refrigerant-side flows of a plurality of intermediate heat exchangers, and a plurality of refrigerant flow switching devices that perform switching of circulation paths are connected with refrigerant pipes, through which a heat-source-side refrigerant circulates pressure sensors that detect the pressure of the heat-source side refrigerant in the refrigerant pipes; a heat medium circuit in which pumps, a plurality of use-side heat exchangers, heat medium flow control devices, and heat-medium-side flows of the intermediate heat exchangers are connected with heat medium pipes, through which a heat medium circulates; and a controller that controls an opening degree of at least one of the heat medium flow control devices to adjust a flow rate of the heat medium, wherein, the controller performs a pressure variation suppressing operation for suppressing a refrigerant pressure variation on a side of the refrigerant circuit by controlling the at least one of the heat medium flow control devices to have a first opening degree so as to allow a certain amount of heat medium to flow through at least one of the use-side heat exchangers of the plurality of the use-side heat exchangers, before the at least one of the use-side heat exchangers of the plurality of the use-side heat exchangers starts operation or performs switching of an operation mode; and characterized in that the controller, after controlling the at least one heat medium flow control devices to have the first opening degree, compares a preset predetermined pressure with a pressure difference between a pressure of the heat-source side refrigerant before the at least one of the heat medium flow control devices is set to have the first opening degree and a pressure of the heat-source side refrigerant after the at least one of the heat medium flow control devices is set to have the first opening degree, and when the pressure difference is smaller than the predetermined pressure, the controller controls the at least one of the heat medium flow control devices whose opening degree has been controlled to the first opening degree to have a second opening degree that is greater than the first opening degree.