Abstract: A metal foil for secondary battery generating less cutting chips at the time of forming an opening and allowed to have a higher aperture ratio without reducing strength and a secondary battery in which short circuit caused by generation of electrode debris can be suppressed are provided. A metal foil 1 for secondary battery is provided with a metal thin plate 2, plural first convex portions 3A formed on a first principal surface 2a of the thin plate 2 by plastic forming and plural second convex portions 3B formed on a second principal surface 2b opposite to the first principal surface 2a by the plastic forming, wherein the convex portions 3A and 3B each have an opening 31 of which aperture plane 31a is orthogonal or substantially orthogonal to the principal surfaces 2a and the 2b.

Abstract: A metal foil for secondary battery generating less cutting chips at the time of forming an opening and allowed to have a higher aperture ratio without reducing strength and a secondary battery in which short circuit caused by generation of electrode debris can be suppressed are provided. A metal foil 1 for secondary battery is provided with a metal thin plate 2, plural first convex portions 3A formed on a first principal surface 2a of the thin plate 2 by plastic forming and plural second convex portions 3B formed on a second principal surface 2b opposite to the first principal surface 2a by the plastic forming, wherein the convex portions 3A and 3B each have an opening 31 of which aperture plane 31a is orthogonal or substantially orthogonal to the principal surfaces 2a and the 2b.