An electro-chemical device comprises a package including a metal film, a battery element sealed within the package, resin layers disposed at least on the inside of a seal part of the package, and a lead extending from the battery element to the outside of the package through between the resin layers at the seal part of the package. The lead has a special form into which the resin of the resin layers bites, so that the lead is firmly buried in the resin layers, whereby the lead is fully inhibited from moving. Therefore, an electro-chemical device having a high quality can be obtained.