To provide a heat sink capable of realizing a heat dissipation effect superior to that of a conventional heat sink with a weight and a size equal to or smaller than those of the conventional heat sink or realizing a heat dissipation effect equal to or greater than that of the conventional heat sink with a weight and a size smaller than those of the conventional heat sink.

In a heat sink 1 consisting of a good heat conductive heat receiving body 2 joined to the case 6 of a heat generating source and a good heat conductive heat dissipation fin 4 attached to the heat receiving body 2 so that heat is conducted, a porous metal foil 3 is used as a heat dissipation fin 4 which is prepared by sandwiching/pressing a metal foil material 12 with a pair of rotary rollers 13 on which many pyramid bodies 15 protruding while meshing each other are arranged on respective cylindrical faces 14, moving the material 12 continuously and piercing the pyramid bodies 15 alternately to the material 12 from both faces. Thus, side walls 17 are broken to a plurality of lines in the apex direction, and many broken protrusions 16 having piercing holes 18 at the apex parts are provided to both faces of the metal foil material 12 in the penetrating direction of the pyramid body 15.