An opposed flow heat exchanger comprising partitions including a corrugated portion for forming passages in a wavefront direction, and flat portions for taking in or out air flows from a predetermined direction at opposite ends of the corrugated portion in the wavefront direction; and flat shape holding plates having a length in a direction of the passages which is not longer than a length of the partitions; wherein the partitions and the shape holding plates are alternately layered so that the corrugated portion of each of the partitions and the shape holding plates contact together, and the flat portion of each of the partitions faces to the flat portion of a partition adjacent thereto, thereby independently forming the passages through the partitions.