A refrigerant passage formed between an inner peripheral surface of a decompression space formed within a body part and an outer peripheral surface of a valve body that changes a refrigerant passage area of a minimum area part functions as a nozzle, and a refrigerant passage formed between an inner peripheral surface of a pressure increase space formed within the body part and an outer peripheral surface of a passage formation member functions as a diffuser to configure an ejector. Further, the valve body and the passage formation member are provided as separated members, and a load of the refrigerant on the valve body is reduced, thereby being capable of downsizing a drive device that displaces the valve body.