An air-conditioning apparatus 100 has at least one intermediate heat exchanger 15 that exchanges heat between a refrigerant changing in two phases or a refrigerant in a supercritical state and a heat medium such as water and anti-freezing fluid different from the refrigerant, a refrigeration cycle in which a compressor 10, a heat-source side heat exchanger 12, at least one expansion valve 16, and a refrigerant-side channel of the intermediate heat exchanger 15 are connected via a pipeline through which the refrigerant flows, and a heat-medium circulation circuit in which a heat-medium side channel of the intermediate heat exchanger 15, a pump 21, and a use-side heat exchanger 26 are connected via a pipeline through which the heat medium flows, in which in the heat-medium circulation circuit, a fourth temperature sensor 34 that detects a temperature of the heat-medium flowing out of the use-side heat exchanger 26 is provided, and leakage of the heat medium from the heat-medium circulation circuit is detected on the basis of a change amount of a detected temperature of the fourth temperature sensor 34.