The present invention provides a liquid-cooling type heat sink which has a high pressure-resistibility and is resistible against the corrosion or erosion-corrosion or electrolytic etching, and a method for its production.The heat sink of the present invention comprises plural base members 21, 31 and 41, the base member being each in plate or block-shape, the base member each having paths 60 shaped on one or both sides of surfaces thereof, and the base members being bonded to each other, wherein a communicating flow path 60a including path 60, through holes 61, 62, and 63, is formed for a cooling medium to flow in and out. The base members are bonded to each other with a solder layer 54 made of Au--Sn alloy or Sn, while a coating layer of Au 53 is formed on each of the inner surfaces of the bonded base members. At the time of making a bond between the base members, the coating layer of Au 53 and the solder layer 54 are diffused to each other, resulting in formation of a bond layer of alloy 55 containing at least 91 wt % of Au and at most 9 wt % of Sn.