A tube for a heat exchanger which has beads (21) formed on a brazing sheet (B) for configuring a tube (2) and tops of the beads brazed with opposed portions within a tube part (20) and a method for manufacturing the tube. The tube part (20) prior to brazing is determined to have a thickness (t') larger than a predetermined thickness (t) and compressed in a direction of its thickness when it is brazed, and the tube which has tops of the beads crushed against or lodged in opposed portions within the tube part. Also a method for manufacturing the tube which can braze the tops of the beads with the opposed portions within the tube more securely and firmly than before. <IMAGE>