The present invention relates to a heat exchanger tube, in which turbulence generating portions placed within a passage of the tube are rounded into curved configurations with predetermined curvatures so that they are hardly damaged or fractured during extrusion to improve machinability and product quality, in which upper and lower circular passages formed in upper and lower sides of a tube body are connected via a connecting passage having the turbulence generating portions so that more passages having a smaller hydraulic diameter can be formed in the tube of the same size without unnecessary waste of tube material, and in which the turbulence generating portions are arranged in a lateral direction (Z-axial direction) of the tube body so that the passage is not filled with condensate films even though a large quantity of condensate is produced to reduce the thickness of the condensate films or break the condensate films to promote refrigerant to be converted into turbulent flow, thereby improving heat transfer ability.