A usage-side air-conditioning apparatus (3a, 3b) comprising: a casing (31a, 31b); a usage-side heat exchanger (33a, 33b), being provided inside the casing, to cool or heat air inside the casing through the use of a refrigerant supplied from a heat-source-side air-conditioning apparatus; an air supply/exhaust mechanism to take room air into the casing from an air-conditioned space, take outdoor air into the casing from outside the air-conditioned space, supply the air inside the casing as supply air to the air-conditioned space, and exhaust the air inside the casing as exhaust air out of the air-conditioned space; and a refrigerant leakage detection device (48a, 48b, 49a, 49b) to detect the refrigerant; wherein the air supply/exhaust mechanism is configured to perform a refrigerant exhaust operation to exhaust the refrigerant out of the air-conditioned space along with the air inside the casing when the refrigerant leakage detection device has detected the refrigerant; characterized in that the usage-side heat exchanger (33a, 33b) is configured to be connected to the heat-source-side air-conditioning apparatus via a refrigerant interconnection pipe (11, 12); a joint (13a, 13b, 14a, 14b) to connect the usage-side heat exchanger to the refrigerant interconnection pipe is provided outside the casing (31a, 31b); the air supply/exhaust mechanism has an inside-outside communication mechanism (47a, 47b) capable of switching between an inside-outside communication state of allowing communication between the casing interior and a usage-side installation space in which the casing is to be provided, and an inside-outside non-communication state of not allowing communication between the casing interior and the usage-side installation space; and the inside-outside communication mechanism is configured to be put in the inside-outside communication state to perform the refrigerant exhaust operation. a casing (31a, 31b); a usage-side heat exchanger (33a, 33b), being provided inside the casing, to cool or heat air inside the casing through the use of a refrigerant supplied from a heat-source-side air-conditioning apparatus; an air supply/exhaust mechanism to take room air into the casing from an air-conditioned space, take outdoor air into the casing from outside the air-conditioned space, supply the air inside the casing as supply air to the air-conditioned space, and exhaust the air inside the casing as exhaust air out of the air-conditioned space; and a refrigerant leakage detection device (48a, 48b, 49a, 49b) to detect the refrigerant; wherein the air supply/exhaust mechanism is configured to perform a refrigerant exhaust operation to exhaust the refrigerant out of the air-conditioned space along with the air inside the casing when the refrigerant leakage detection device has detected the refrigerant; characterized in that the usage-side heat exchanger (33a, 33b) is configured to be connected to the heat-source-side air-conditioning apparatus via a refrigerant interconnection pipe (11, 12); a joint (13a, 13b, 14a, 14b) to connect the usage-side heat exchanger to the refrigerant interconnection pipe is provided outside the casing (31a, 31b); the air supply/exhaust mechanism has an inside-outside communication mechanism (47a, 47b) capable of switching between an inside-outside communication state of allowing communication between the casing interior and a usage-side installation space in which the casing is to be provided, and an inside-outside non-communication state of not allowing communication between the casing interior and the usage-side installation space; and the inside-outside communication mechanism is configured to be put in the inside-outside communication state to perform the refrigerant exhaust operation.