An air-conditioning apparatus comprising: a refrigeration cycle configured by connecting, by a pipe, a compressor configured to compress a heat source side refrigerant, a refrigerant flow switching device configured to switch between paths for circulation of the heat source side refrigerant, a heat source side heat exchanger configured to allow the heat source side refrigerant to exchange heat, an expansion device configured to regulate a pressure of the heat source side refrigerant, and at least one intermediate heat exchanger configured to exchange heat between the heat source side refrigerant and a heat medium different from the heat source side refrigerant; a heat medium circuit configured by connecting, by a pipe, at least one pump configured to circulate the heat medium for heat exchange by the intermediate heat exchanger, a use side heat exchanger configured to exchange heat between the heat medium and air in an air-conditioning target space, and a flow switching valve configured to switch between passing a heated heat medium through the use side heat exchanger and passing a cooled heat medium through the use side heat exchanger; an incoming heat medium temperature detecting device configured to detect a temperature at a heat medium inlet of the intermediate heat exchanger; an outgoing heat medium temperature detecting device configured to detect a temperature at a heat medium outlet of the intermediate heat exchanger; an air-conditioning target temperature detecting device configured to detect the temperature of air flowing into the use side heat exchanger; and a controller configured to calculate an actual temperature efficiency ratio based on a temperature at a heat medium inlet of the heat exchanger in the heat medium circuit, the temperature at the heat medium outlet, and the temperature of the air flowing into the use side heat exchanger and determine whether a flow rate of the heat medium in the heat medium circuit is abnormal based on the actual temperature efficiency ratio and a set reference temperature efficiency ratio. a refrigeration cycle configured by connecting, by a pipe, a compressor configured to compress a heat source side refrigerant, a refrigerant flow switching device configured to switch between paths for circulation of the heat source side refrigerant, a heat source side heat exchanger configured to allow the heat source side refrigerant to exchange heat, an expansion device configured to regulate a pressure of the heat source side refrigerant, and at least one intermediate heat exchanger configured to exchange heat between the heat source side refrigerant and a heat medium different from the heat source side refrigerant; a heat medium circuit configured by connecting, by a pipe, at least one pump configured to circulate the heat medium for heat exchange by the intermediate heat exchanger, a use side heat exchanger configured to exchange heat between the heat medium and air in an air-conditioning target space, and a flow switching valve configured to switch between passing a heated heat medium through the use side heat exchanger and passing a cooled heat medium through the use side heat exchanger; an incoming heat medium temperature detecting device configured to detect a temperature at a heat medium inlet of the intermediate heat exchanger; an outgoing heat medium temperature detecting device configured to detect a temperature at a heat medium outlet of the intermediate heat exchanger; an air-conditioning target temperature detecting device configured to detect the temperature of air flowing into the use side heat exchanger; and a controller configured to calculate an actual temperature efficiency ratio based on a temperature at a heat medium inlet of the heat exchanger in the heat medium circuit, the temperature at the heat medium outlet, and the temperature of the air flowing into the use side heat exchanger and determine whether a flow rate of the heat medium in the heat medium circuit is abnormal based on the actual temperature efficiency ratio and a set reference temperature efficiency ratio.