A battery pack that allows easy application of injection molding in the formation of a battery case and is capable of improving fastening strength of the case components. For this purpose, the battery pack comprises a plurality of battery cells; a circuit module electrically connected to the plurality of battery cells; and a case accommodating the plurality of battery cells and the circuit module, wherein the case includes a first case shaped in the form of an open box and having a plurality of coupling protrusions formed thereon and a second case shaped in the form of an open box and having a plurality of coupling holes engaging with the plurality of coupling protrusions in order to couple the second case with the first case.