The present invention comprises steps of forming an opening portion in a battery case; aspirating an electrolyte solution from the interior of the battery case through the opening portion and into a sealed and depressurized electrolyte solution recovery trap; injecting a solvent containing no electrolyte from a solvent tank through the opening portion, and into the battery case; and aspirating a mixed solution from the interior of the battery case through the opening portion and into the sealed and depressurized electrolyte solution recovery trap. By performing the above-mentioned process, battery constitutive members including the battery case can be disassembled and recovered efficiently in large quantities.