An evaporator includes a downwind-side heat exchanging part and an upwind-side heat exchanging part. In the heat exchanging part, paths are formed by partitions. In the evaporator, the flowing direction of coolant flowing in the upwind-side path is opposite to the flowing direction of the coolant flowing in the downwind-side path opposing to the upwind-side path. The number of heat exchanging passages in the path where the coolant rises is smaller than the number of heat exchanging passages in the paths where the coolant downs. As a result, the evaporator enables an increasing of the quantity of coolant flowing in the paths. Thus, if superimposing the upwind-side heat exchanging part on the downwind-side heat exchanging part, then it is possible to reduce an area causing a rise in blowout temperature of the coolant due to its short supply.