An air-conditioning apparatus, comprising: a refrigerant circuit configured to circulate refrigerant therethrough; and an indoor unit configured to accommodate at least a load-side heat exchanger of the refrigerant circuit , the indoor unit including: a casing ; a drain pan , which is provided inside the casing , and is configured to receive condensate water generated in the load-side heat exchanger ; and a refrigerant detection unit provided below the drain pan inside the casing , the refrigerant detection unit including: a sensor configured to detect leakage of the refrigerant; a sensor cover configured to cover the sensor from a front surface side of the sensor ; and a mount plate arranged on a back surface side of the sensor , the sensor cover including: a roof portion arranged above the sensor ; and a side surface portion arranged on the front surface side or a side surface side of the sensor below the roof portion , the roof portion having an eaves portion projecting outward with respect to the side surface portion , the side surface portion having at least one first opening port configured to introduce air to an inside of the sensor cover therethrough, and the mount plate having a slit into which one end of the roof portion is inserted. a refrigerant circuit configured to circulate refrigerant therethrough; and an indoor unit configured to accommodate at least a load-side heat exchanger of the refrigerant circuit , the indoor unit including: a casing ; a drain pan , which is provided inside the casing , and is configured to receive condensate water generated in the load-side heat exchanger ; and a refrigerant detection unit provided below the drain pan inside the casing , the refrigerant detection unit including: a sensor configured to detect leakage of the refrigerant; a sensor cover configured to cover the sensor from a front surface side of the sensor ; and a mount plate arranged on a back surface side of the sensor , the sensor cover including: a roof portion arranged above the sensor ; and a side surface portion arranged on the front surface side or a side surface side of the sensor below the roof portion , a casing ; a drain pan , which is provided inside the casing , and is configured to receive condensate water generated in the load-side heat exchanger ; and a refrigerant detection unit provided below the drain pan inside the casing , the refrigerant detection unit including: a sensor configured to detect leakage of the refrigerant; a sensor cover configured to cover the sensor from a front surface side of the sensor ; and a mount plate arranged on a back surface side of the sensor , the sensor cover including: a roof portion arranged above the sensor ; and a side surface portion arranged on the front surface side or a side surface side of the sensor below the roof portion , a sensor configured to detect leakage of the refrigerant; a sensor cover configured to cover the sensor from a front surface side of the sensor ; and a mount plate arranged on a back surface side of the sensor , the sensor cover including: a roof portion arranged above the sensor ; and a side surface portion arranged on the front surface side or a side surface side of the sensor below the roof portion , a roof portion arranged above the sensor ; and a side surface portion arranged on the front surface side or a side surface side of the sensor below the roof portion , the roof portion having an eaves portion projecting outward with respect to the side surface portion , the side surface portion having at least one first opening port configured to introduce air to an inside of the sensor cover therethrough, and the mount plate having a slit into which one end of the roof portion is inserted. <EOS>