A refrigeration cycle apparatus comprising: a refrigerant circuit configured to circulate refrigerant to a compressor, a plurality of indoor heat exchangers (42A, 42B) each configured to serve as a condenser or an evaporator, a plurality of expansion valves (41A, 41B), and an outdoor heat exchanger configured to serve as an evaporator or a condenser, the compressor being connected to the plurality of indoor heat exchangers (42A, 42B) by a first extension pipe, the expansion valves (41A, 41B) being connected to the the outdoor heat exchanger by a second extension pipe; a detection unit configured to detect an operating state amount of the refrigerant circuit; a controller configured to execute a refrigerant-leakage detection operation of detecting refrigerant leakage by calculating a refrigerant amount in the refrigerant circuit based on the operating state amount detected by the detection unit and comparing the calculated refrigerant amount with a reference refrigerant amount; an outdoor unit including the compressor, a four-way valve configured to cause a heating operation and a cooling operation to be executed by switching a flow of the refrigerant, and the outdoor heat exchanger; and a plurality of indoor units (4A, 4B) each including one of the plurality of expansion valves (41A, 41B), and one of the plurality of indoor heat exchangers (42A, 42B), the outdoor unit being connected to each of the plurality of indoor units (4A, 4B) by the first extension pipe and the second extension pipe, characterized in that the controller, in the refrigerant-leakage detection operation, is configured to cause each of the plurality of indoor heat exchangers (42A, 42B) to serve as the condenser so that all the plurality of indoor units (4A, 4B) operate in the heating operation, cause the outdoor heat exchanger to serve as the evaporator, control the plurality of expansion valves to cause a refrigerant state at an outlet of the condenser to become a saturated liquid state, control a quality of the refrigerant at an outlet of the second extension pipe to be in a range from 0.1 to 0.7, and control frequency of the compressor to be compressor frequency being a half of rated compressor frequency. a refrigerant circuit configured to circulate refrigerant to a compressor, a plurality of indoor heat exchangers (42A, 42B) each configured to serve as a condenser or an evaporator, a plurality of expansion valves (41A, 41B), and an outdoor heat exchanger configured to serve as an evaporator or a condenser, the compressor being connected to the plurality of indoor heat exchangers (42A, 42B) by a first extension pipe, the expansion valves (41A, 41B) being connected to the the outdoor heat exchanger by a second extension pipe; a detection unit configured to detect an operating state amount of the refrigerant circuit; a controller configured to execute a refrigerant-leakage detection operation of detecting refrigerant leakage by calculating a refrigerant amount in the refrigerant circuit based on the operating state amount detected by the detection unit and comparing the calculated refrigerant amount with a reference refrigerant amount; an outdoor unit including the compressor, a four-way valve configured to cause a heating operation and a cooling operation to be executed by switching a flow of the refrigerant, and the outdoor heat exchanger; and a plurality of indoor units (4A, 4B) each including one of the plurality of expansion valves (41A, 41B), and one of the plurality of indoor heat exchangers (42A, 42B), the outdoor unit being connected to each of the plurality of indoor units (4A, 4B) by the first extension pipe and the second extension pipe, characterized in that the controller, in the refrigerant-leakage detection operation, is configured to cause each of the plurality of indoor heat exchangers (42A, 42B) to serve as the condenser so that all the plurality of indoor units (4A, 4B) operate in the heating operation, cause the outdoor heat exchanger to serve as the evaporator, control the plurality of expansion valves to cause a refrigerant state at an outlet of the condenser to become a saturated liquid state, control a quality of the refrigerant at an outlet of the second extension pipe to be in a range from 0.1 to 0.7, and control frequency of the compressor to be compressor frequency being a half of rated compressor frequency.