NOVELTY - The assembly (300) has a battery module (200) provided with a cell unit constituted by prismatic type secondary battery (10). The upper and lower cases (210,220) are set to surround outer surfaces of battery modules. A screw thread (211) is vertically formed on an upper surface of upper case and a lower surface of lower case, to mutually fasten and fix the upper case and lower case. An arched shaped screw thread (212) is formed horizontally on the front surface and rear surface of the upper case and lower case for position fixing or mounting of the battery module assembly.    USE - Battery module assembly of middle or large-sized battery pack used in device such as electric vehicle, diesel vehicle and plug-in hybrid electric vehicle (all claimed). Can also be used in wireless mobile apparatus and power storage system.    ADVANTAGE - The welding reliability of the battery module assembly can be improved by providing the bus bar in the front side of battery modules. As several cell units are arranged in parallel connection, the internal resistance of the assembly of battery module can be minimized. As the insulating tape is adhered to the surrounding surface of the sealing portion of the battery, the insulation resistance property of the battery module can be improved. As the battery modules are combined using the minimum elements within the upper case and lower case, the space of the battery pack can be optimized so as to improve the assembly performance, structural stability, and fixing and installation effect of the battery module. The weight of the battery pack can be reduced. The separation of the sealing portion of the battery cell can be prevented. The service lifetime of the battery pack can be improved by preventing the generation of the heat in the battery pack. The short circuit between outside input-output terminals of the battery module assembly can be prevented by stepped pulley.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for large-sized battery pack.    DESCRIPTION OF DRAWING(S) - The drawing shows the perspective view of the battery pack.    Prismatic type secondary battery (10)    Battery module (200)    Upper case (210)    Screw threads (211,212)    Lower case (220)    Battery module assembly (300)