A battery case and method of production of the same realizing smaller size, higher mountability, longer service life, and lower cost than in the past, that is, a battery case comprising a container body and a container cover, in which battery case, one or both of the container body and the container cover are made from a laminated steel sheet comprised of a plated steel sheet on which a film having a polyolefin-based resin as a main constituent is laminated, a joined part of the container body and the container cover has a welded part of the plated steel sheet, a melt bonded part of the film, and a gap part between the welded part and the melt bonded part, where a length of gap part/thickness of plated steel sheet ≤10.0 and a length of gap part/length of joined part