Disclosed is a method for manufacturing a battery pack which has an upper plate configured to have a seating surface, on which battery modules are seated, and a plurality of members configured to separate the seating surface of the upper plate into a plurality of regions. The method includes calculating height tolerances of the seating surface in the respective regions, determining application amounts of the gap filler in the respective regions based on the calculated height tolerances in the respective regions, and applying the determined application amounts of the gap filler in the respective regions.