A refrigeration cycle apparatus, comprising: a refrigeration cycle (40, 310) configured to circulate refrigerant by a compressor; a heat exchanger unit (1, 2, 400, 300) configured to accommodate at least a heat exchanger (7, 202, 5, 201) of the refrigeration cycle (40, 310); and a controller (30, 301, 401) configured to control the heat exchanger unit (1, 2, 400, 300), the heat exchanger unit (1, 2, 400, 300) comprising a refrigerant detection unit configured to detect the refrigerant; the controller (30, 301, 401) comprising a control board to which the refrigerant detection unit is unremovably connected, and a nonvolatile memory provided on the control board, the nonvolatile memory being provided with a first failure history storage area for storing any one of first information indicating a state of having no failure history in the refrigerant detection unit and second information indicating a state of having a failure history in the refrigerant detection unit, characterized in that changing of the information stored in the first failure history storage area is allowed only in one way from the first information to the second information, and in that the controller (30, 301, 401) is configured to change the information stored in the first failure history storage area from the first information to the second information when the refrigerant detection unit fails, stop the compressor when the information stored in the first failure history storage area is changed from the first information to the second information, and prevent the compressor from starting until the information stored in the first failure history storage area is changed from the second information to the first information by replacement of the control board. a refrigeration cycle (40, 310) configured to circulate refrigerant by a compressor; a heat exchanger unit (1, 2, 400, 300) configured to accommodate at least a heat exchanger (7, 202, 5, 201) of the refrigeration cycle (40, 310); and a controller (30, 301, 401) configured to control the heat exchanger unit (1, 2, 400, 300), the heat exchanger unit (1, 2, 400, 300) comprising a refrigerant detection unit configured to detect the refrigerant; the controller (30, 301, 401) comprising a control board to which the refrigerant detection unit is unremovably connected, and a nonvolatile memory provided on the control board, the nonvolatile memory being provided with a first failure history storage area for storing any one of first information indicating a state of having no failure history in the refrigerant detection unit and second information indicating a state of having a failure history in the refrigerant detection unit, characterized in that a control board to which the refrigerant detection unit is unremovably connected, and a nonvolatile memory provided on the control board, the nonvolatile memory being provided with a first failure history storage area for storing any one of first information indicating a state of having no failure history in the refrigerant detection unit and second information indicating a state of having a failure history in the refrigerant detection unit, characterized in that changing of the information stored in the first failure history storage area is allowed only in one way from the first information to the second information, and in that the controller (30, 301, 401) is configured to change the information stored in the first failure history storage area from the first information to the second information when the refrigerant detection unit fails, stop the compressor when the information stored in the first failure history storage area is changed from the first information to the second information, and prevent the compressor from starting until the information stored in the first failure history storage area is changed from the second information to the first information by replacement of the control board. change the information stored in the first failure history storage area from the first information to the second information when the refrigerant detection unit fails, stop the compressor when the information stored in the first failure history storage area is changed from the first information to the second information, and prevent the compressor from starting until the information stored in the first failure history storage area is changed from the second information to the first information by replacement of the control board.