An air-conditioning apparatus comprising a refrigerant circuit in which a compressor, a flow passage switching device, an outdoor heat exchanger, an indoor heat exchanger, a refrigerant container, a first expansion device and a second expansion device are connected by pipes; the compressor compressing and discharging sucked refrigerant, the flow passage switching device switching a flow passage to a cooling flow passage during cooling operation and to a heating flow passage during heating operation, the outdoor heat exchanger being located outside of a room and causing heat exchange to be performed with refrigerant, the indoor heat exchanger being located inside of a room and causing heat exchange to be performed between air in an air-conditioned space and the refrigerant, the refrigerant container storing excessive refrigerant, the first expansion device depressurizing the refrigerant between the outdoor heat exchanger and the refrigerant container, and the second expansion device depressurizing the refrigerant between the indoor heat exchanger and the refrigerant container, characterised in that the indoor heat exchanger and the outdoor heat exchanger have inner volumes satisfying a relationship of an inner volume of the indoor heat exchanger < an inner volume of the outdoor heat exchanger, and in that the air-conditioning apparatus further comprises a controller which is configured to, when performing cooling operation, perform control so as to allow the flow passage switching device to switch the flow passage to the heating flow passage and allow an opening degree of the second expansion device to be larger than an opening degree of the first expansion device, and start the compressor, and when a judgment is made that a set time that is set in advance has elapsed from the start of the compressor, perform control so as to allow the opening degree of the first expansion device and the opening degree of the second expansion device to be initial opening degrees for the cooling operation, wherein the set time is set to a time period that is equal to or shorter than a time period during which a discharge pressure of the refrigerant discharged from the compressor reaches a design pressure that is designed in the refrigerant circuit. the compressor compressing and discharging sucked refrigerant, the flow passage switching device switching a flow passage to a cooling flow passage during cooling operation and to a heating flow passage during heating operation, the outdoor heat exchanger being located outside of a room and causing heat exchange to be performed with refrigerant, the indoor heat exchanger being located inside of a room and causing heat exchange to be performed between air in an air-conditioned space and the refrigerant, the refrigerant container storing excessive refrigerant, the first expansion device depressurizing the refrigerant between the outdoor heat exchanger and the refrigerant container, and the second expansion device depressurizing the refrigerant between the indoor heat exchanger and the refrigerant container, characterised in that the indoor heat exchanger and the outdoor heat exchanger have inner volumes satisfying a relationship of an inner volume of the indoor heat exchanger < an inner volume of the outdoor heat exchanger, and in that the air-conditioning apparatus further comprises a controller which is configured to, when performing cooling operation, perform control so as to allow the flow passage switching device to switch the flow passage to the heating flow passage and allow an opening degree of the second expansion device to be larger than an opening degree of the first expansion device, and start the compressor, and when a judgment is made that a set time that is set in advance has elapsed from the start of the compressor, perform control so as to allow the opening degree of the first expansion device and the opening degree of the second expansion device to be initial opening degrees for the cooling operation, wherein the set time is set to a time period that is equal to or shorter than a time period during which a discharge pressure of the refrigerant discharged from the compressor reaches a design pressure that is designed in the refrigerant circuit.