A heat exchanger comprising a heat exchange core (1) including a plurality of tubes (2) flowing a medium for heat exchange and a pair of tanks (4) to which ends of said tubes are connected, each tube formed by shaping a plate member (200) not clad with a row laminated brazing material and having a sacrifice layer (210) on an outer surface thereof and a plurality of recessed portions (203) formed on an outer surface of said sacrifice layer and filled with a brazing material (R).