A refrigeration cycle system, comprising: a refrigeration cycle apparatus comprising a refrigeration cycle configured to circulate refrigerant by a compressor, and a controller configured to control the refrigeration cycle; and a refrigerant detection unit (605, 608) configured to detect the refrigerant, the controller comprising a control board (615a, 616a) to which the refrigerant detection unit (605, 608) is unremovably connected, and a nonvolatile memory provided on the control board (615a, 616a), the nonvolatile memory being provided with a leakage history storage area for storing any one of first information indicating a state of absence of refrigerant leakage history and second information indicating a state of presence of a refrigerant leakage history, wherein changing of the information stored in the leakage history storage area is allowed only in one way from the first information to the second information, and the controller is configured to change the information stored in the leakage history storage area from the first information to the second information when detecting the leakage of the refrigerant, stop the compressor when the information stored in the leakage 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 leakage history storage area is changed from the second information to the first information by replacement of the control board. a refrigeration cycle apparatus comprising a refrigeration cycle configured to circulate refrigerant by a compressor, and a controller configured to control the refrigeration cycle; and a refrigeration cycle configured to circulate refrigerant by a compressor, and a controller configured to control the refrigeration cycle; and a refrigerant detection unit (605, 608) configured to detect the refrigerant, the controller comprising a control board (615a, 616a) to which the refrigerant detection unit (605, 608) is unremovably connected, and a nonvolatile memory provided on the control board (615a, 616a), the nonvolatile memory being provided with a leakage history storage area for storing any one of first information indicating a state of absence of refrigerant leakage history and second information indicating a state of presence of a refrigerant leakage history, wherein a control board (615a, 616a) to which the refrigerant detection unit (605, 608) is unremovably connected, and a nonvolatile memory provided on the control board (615a, 616a), the nonvolatile memory being provided with a leakage history storage area for storing any one of first information indicating a state of absence of refrigerant leakage history and second information indicating a state of presence of a refrigerant leakage history, wherein changing of the information stored in the leakage history storage area is allowed only in one way from the first information to the second information, and the controller is configured to change the information stored in the leakage history storage area from the first information to the second information when detecting the leakage of the refrigerant, stop the compressor when the information stored in the leakage 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 leakage 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 leakage history storage area from the first information to the second information when detecting the leakage of the refrigerant, stop the compressor when the information stored in the leakage 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 leakage history storage area is changed from the second information to the first information by replacement of the control board.