a plurality of tubes each formed by bonding a pair of plates with each other, the tube having two flow channels formed therein, a partition bead interposed between the two flow channels, and pairs of cups formed at the upper and lower ends thereof in a row in such a manner as to communicate with each flow channel, the cups being coupled to each other so as to form upper and lower tanks;

inlet and outlet pipes respectively communicated with said two flow channels for allowing flow-in and flow-out of refrigerant;

an inlet side heat exchange part adapted to communicate with the inlet pipe at the tubes;

an outlet side heat exchange part adapted to communicate with the outlet pipe at the tubes;

fluid communication means for intercommunicating predetermined areas of the tanks to which the inlet and/or outlet pipes are mounted by communicating the inlet and outlet side heat exchange parts with each other in such a fashion that all of the inlet and outlet side heat exchange parts adjacent to each other in an air flow direction have the same refrigerant flow direction, and such that the refrigerant flow direction through the fluid communication means is not the same; and

blank plates dividing the inlet and outlet side heat exchange parts into a plurality of heat exchange zones, the blank plates being formed by closing cups located diagonally on both ends of the fluid communication means in such a fashion that portions of the heat exchange zones including at least one of the tubes and communicating with each other via the fluid communication means are mutually overlapped.