Provided is a tube for a heat exchanger, and more particularly, a tube for a heat exchanger forming a channel of a heat exchange medium and including a plurality of inner holes having inner spaces separated in a width direction by a plurality of inner walls extending in a longitudinal direction, in which a thickness of outer walls of certain regions at both ends in the width direction of the tube is formed to be thicker than that of the remaining regions, thereby improving heat exchange performance and preventing corrosion.