Disclosed is a battery module, which includes a plurality of battery cells, each having an electrode lead; and a bus bar configured to electrically the electrode leads of the plurality of battery cells, the bus bar having a plurality of insert slits into which the electrode leads are inserted, and legs formed at both sides of each insert slit, wherein the legs located adjacent to each other with the insert slit being interposed therebetween are directly bonded to each other by a welding portion or connected to each other by a solder in a state of being pressed toward each other.