The object of the present invention is to provide a simple-construction four-way switching valve which is simple in construction and excellent in sealability, performs switching of the operation mode without producing unusual noise, and is reduced in the number of manufacturing steps through elimination of externally-mounted parts for pressure passages. Main valves having a poppet valve structure constitute a three way switching valve which is operated by a pilot valve, for switching the high-pressure refrigerant introduced into the port T1 to the port T2 or to the port T3, and main valves which have a poppet valve structure and are switched by the differential pressure between the ports T2 and T3 constitute a low-pressure three-way switching valve. This makes it possible to improve the sealability, prevent unusual noise from being generated during switching of the operation mode, and simplify the construction. Further, the pressure passage for releasing the back pressures of the pistons that actuate the main valves is formed through the body, which dispenses with externally-mounted parts, such as tubes, so that the number of parts is reduced to make it possible to reduce the size.