The present invention provides a battery module having a plurality of battery cells in sheet-form which are sequentially laminated, in which the battery module is formed from two or more hexahedral cell units, laminated and connected in series, and the cell unit consists of two or more battery cells connected in series, and adhered to each other. Electrode terminals (outermost electrode terminals) of the outermost battery cells from among the cell units are connected to an external input/output terminal of the battery module, and have wider vertical cross-sectional areas than remaining the electrode terminals of the battery cells so that a break due to an external impact can be prevented.