A heat exchanger for a supercritical refrigerating cycle, comprising tubes 510 and tanks 520 which have plural hollow portions 520a and slots 521a for insertion of the ends of the tubes formed, wherein a sectional outline of the hollow portions of the tanks has an approximately semicircular shape with a side corresponding to the diameter directed to the side of the slots. And, the partition members each 523 is disposed between the plate bodies 521 and the tank member 522. The tanks are formed by assembling plate bodies 521 with slots formed and tank members 522 with plural curves formed to configure hollow portions, and the plate bodies are provided with communicating recesses 521b for communicating plural hollow portions. Besides, the partition members 523 for division of the hollow portions are disposed between the plate bodies and the tank members, holes 521c, 522a are formed in required portions of the plate bodies and the tank members, and plural projections 523a to be inserted through the individual holes are formed on the partition members and caulked after being inserted through the holes.