A refrigerant evaporator for a refrigeration cycle provided with a heat exchanging unit, comprising a passageway to be cooled and a cooling passageway, and an evaporating unit for cooling the air, wherein a part of the inflowing refrigerant is divided, passed through a throttle to be reduced in pressure, and then passed through the cooling passageway of the heat exchanging unit, the inflowing refrigerant passing through the passageway to be cooled is cooled and completely changed to the liquid state and then passed into the evaporating unit, whereby the refrigerant is uniformly distributed to a plurality of refrigerant passageways of the evaporating unit.