Battery packaging material wherein a sheet-like laminated body is formed by sequentially stacking at least a base layer, metal layer, and sealant layer, the battery packaging material being equipped with substantially rectangular space that is formed to protrude from the sealant layer side toward the base layer side, and accommodates a battery element on the sealant layer side. In planar view from the base layer side view, a first and second curved sections are provided from the center portion toward the battery packaging material end parts, in a cross section in the thickness direction on a line connecting opposing corner parts protruding in a substantially rectangular shape. The thickness (a) of the metal layer at the first curved section, (c) of the metal layer at the second curved section, and (b) of the metal layer at the section located between the first and second curved sections, satisfy the following relationship a≥b>c or a≥c>b.