PROBLEM TO BE SOLVED: To improve the brazability at a joint part, in a tube for heat exchangers.SOLUTION: A tubular member 20 that constitutes a tube for a heat exchanger comprises a pair of flat plate sections 21, 22 that are aligned in parallel so as to face one another in the minor-axis direction of the channel cross section, and a pair of curved sections 23, 24 that face one another in the major-axis direction of the channel cross section and connect the pair of flat plate sections 21, 22 to one another. One of the curved sections 23, 24 constitutes a joint part at which an outer wall portion 241, which extends from an end of the pair of flat plate sections 21, 22 and constitutes a part of the outer wall of the tubular member 20, and an inner wall portion 242, which extends from an end of the pair of flat plate sections 21, 22 and constitutes a part of the inner wall of the tubular member 20, overlap and are joined by brazing. Further, the inner wall portion 242 is joined in a manner such that the portion facing the outer wall portion 241 is closely adhered to the outer wall portion 241, and the leading end 244 facing the flat section 21 is spaced apart from the flat plate section 21.