An ejector has a nozzle, a body, a passage defining member and a drive portion. The body has a refrigerant suction port and a pressure increasing portion. A nozzle passage is defined between an inner surface of the nozzle and an outer surface of the passage defining member and has a minimum sectional area portion, a tapered portion, and an expansion portion. The minimum sectional area portion has a smallest passage sectional area. The tapered portion is located upstream of the minimum sectional area portion in a refrigerant flow direction and has a passage sectional area decreasing toward the minimum sectional area portion gradually. The expansion portion is located downstream of the minimum sectional area portion in the refrigerant flow direction and has a passage sectional area increasing gradually. The passage defining member has a groove that is recessed to increase the passage sectional area of the nozzle passage.