COOLING/HEATING SWITCHING UNIT

A cooling/heating switching unit is provided that is capable of simply and reliably detecting leak of refrigerant. The cooling/heating switching unit includes: a fitting 37 and a fitting 38 that have a high/low-pressure gas main pipe 24 and a low-pressure gas main pipe 27 connected thereto, respectively, wherein the pipes 24, 27 are linked to an outdoor unit 10; a fitting 39 that has an indoor-unit connection pipe 28 connected thereto, wherein the pipe 28 is linked to an indoor unit 40; an expansion valve for high/low-pressure gas pipe 31, an expansion valve for low-pressure gas pipe 32, and expansion-valve driving sections 33 and 34 that selectively connect the fitting 37 or the fitting 38 with the fitting 39 via a refrigerant pipe to control a flow direction of refrigerant; a housing 50 that houses the refrigerant pipe; a heat insulating material that fills inside of the housing 50 to insulate the refrigerant pipe arranged inside of the housing 50 from heat; and a refrigerant leak detection sensor 81 that is installed outside of the housing 50 to detect leaked refrigerant.