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 (232, 232a, 232b) 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 (231a, 231b) projecting outward with respect to the side surface portion (232, 232a, 232b), the side surface portion (232, 232a, 232b) having at least one first opening port (234a, 234b) 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 (232, 232a, 232b) 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 (232, 232a, 232b) 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 (232, 232a, 232b) 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 (232, 232a, 232b) 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 (231a, 231b) projecting outward with respect to the side surface portion (232, 232a, 232b), the side surface portion (232, 232a, 232b) having at least one first opening port (234a, 234b) 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.