Discussed is an apparatus and a method for manufacturing a battery module, and the apparatus for manufacturing battery module includes a support member for supporting a module frame including a bottom part and two side surface parts facing each other, a side surface guide member configured to align the two side surface parts of the module frame, and a spreading jig located at an end of the side surface guide member and configured to spread opposite ends of the two side surface parts of the module frame, and a battery cell stack is inserted into an interior of the module frame by the spreading jigs.