The carrier-foil-attached ultra-thin copper foil according to one embodiment of the present invention comprises a carrier foil, a release layer, a first ultra-thin copper foil, a Cu-Al bonding strength improvement layer, an A1 layer, and a second ultra-thin copper foil, wherein the release layer may comprise a first metal (A3) having peeling properties, and a second metal (B3) and third metal (C3)facilitating the plating of the first metal (A3).