A surface-treated steel sheet for battery containers is provided. The surface-treated sheet is used to form a battery container for a battery. The battery uses a nonaqueous electrolytic solution as an electrolytic solution. The surface-treated steel sheet includes a base material made of steel and an iron-nickel diffusion layer formed by performing thermal diffusion treatment after forming a nickel plating layer at least on a surface of the base material to be located at the inner surface side of the battery container. The iron-nickel diffusion layer has an outermost layer of which a ratio of Ni and Fe is 7.5 or less as a molar ratio of Ni/Fe. The iron-nickel diffusion layer has a thickness of 0.6 μm or more.