A metallic double-sided element comprising a coupling head includes: thin flat plate portions; coupling convex portions projecting at a central portion in the right-left direction of the thin flat plate portion; right and left raised portions which are raised in the front surface-rear surface direction from the thin flat plate portion disposed on the right and left sides of each of the coupling convex portions and integrated with the body portion; and a coupling concave portion which is formed surrounded by the coupling convex portion, the right and left raised portions and the body portion, wherein each of the right and left raised portions has a slope portion which is inclined from a front edge toward the body portion such that the slope portion rises thereof, part of each side face of the right and left slope portions is integrated with part of right and left side faces of the coupling convex portion in a face bonding manner.