Abstract: The structure of header-tank for a heat exchanger comprises a plurality of tubes which are arranged in a row along an air-blowing direction to be spaced apart from each other at a certain intervals; fins which are interposed between the tubes so as to increase a heat exchange surface area with respect to air flowing between the tubes; and a pair of header-tanks which comprises a header having a tube insertion hole and a tank coupled with the header and in which heat exchange medium is flowed, wherein the header is bent at a surface, in which the tube insertion hole is formed, so as to form a bending portion in a height direction, and the bending portion is formed with a plurality of taps 5, and the tank is formed with a coupling portion coupled to the bending portion of the header, and a coupling groove which is recessed inside tank at the same position as the tap along a longitudinal direction and in which the tap is bent and inserted.