the tube body 70 which is smaller than the bowl shaped bulging wall portions 80 80 and the protrusion members 100 100 are defined as connecting portions 90 90 at the bulging leading ends of the bowl shaped bulging wall portions 80 80 opposite bowl shaped bulging portions 80 80 are linearly brought into contact with each other by the protrusion members 100 100 at these connecting portions 90 90 to be soldered to each other in the heat exchanger tube a having this configuration oxides of the soldering material separated by flux speedily flow out of the linear contact portions of the plurality of protrusion members 100 100 at the leading end connecting portions 90 90 of the bowl shaped bulging wall portions 80 80 so as to allow improved soldering accordingly the opposite wall portions 30 and 40 can be connected to each other without occurrence of weld failures further the opposite wall portions 30 and 40 are further firmly connected to each other at positions by the plurality of the bowl shaped bulging wall portions 80 80 furthermore a fluid flowing in the passage 60 generates turbulence flows at the plurality of the bowl shaped bulging wall portions 80 80 thus the fluid is uniformly agitated in the tube body 70 according to the heat exchanger tube a shown in fig1.