Disclosed herein is a middle- or large-sized battery module having a structure in which two or more plate-shaped secondary battery cells (‘battery cells’) are arranged in a lateral direction thereof, wherein the battery cells have electrode terminals arranged in the same direction, plate-shaped electrode terminal connecting members to electrically connect the battery cells to one another are electrically connected to oriented surfaces of the electrode terminals of the battery cells, each of the electrode terminal connecting members is provided at a top and/or bottom thereof with a coupling structure to interconnect electrode terminal connecting members, and at least one end of an insulating joint member coupled in the coupling structure is supported by a module case.