A unit for a refrigerant cycle device includes an ejector that has a nozzle part which decompresses refrigerant, and a refrigerant suction port from which refrigerant is drawn by a high-speed refrigerant flow jetted from the nozzle part, a first evaporator connected to the outlet of the ejector, and a second evaporator connected to the refrigerant suction port of the ejector. One of the first evaporator and the second evaporator has a tank structure that includes a tank for distributing refrigerant into or for collecting the refrigerant from refrigerant passages of a heat exchanging part. The tank has therein a first space through which the refrigerant discharged from the outlet of the ejector flows into a heat exchanging part of the first evaporator, and a second space through which the refrigerant to be drawn into the refrigerant suction port flows into a heat exchanging part of the second evaporator.