An evaporator used in a car air conditioner satisfies a a relation of 0.9≦P1/P2≦1.1, where P1 is the passage cross sectional area of each portion of a refrigerant discharge passage of a refrigerant inlet outlet member of the evaporator, and P2 is the passage cross sectional area of a pipe which establishes communication between a second refrigerant passage of an expansion valve and a compressor. Preferably, relations of W1>W2 and H1>H2 are satisfied, where W1 and H1 are the internal width and height of an upstream end portion of a straight portion of an outward bulged portion of a third plate of the refrigerant inlet outlet member, and W2 and H2 are the internal width and height of a downstream end portion of the outward bulged portion.