The automobile manufacture is a typical integrated assembly production that the numerous parts are committed sequentially to the assembly line. In this type of automobile manufacture, WBS (white body storage) and PBS (paint body storage) are operated to adjust the production sequence and to buffer. Starvation (impossibility of production owing to the insufficient supply) or blocking (impossibility of production owing to the over capacity) could occur in some chance, hence, both storages (WBS, PBS) are integrated as a prevention. This system is called integrated storage. In this paper, we suggest the simulation model of ‘WBS-PBS integrated storage’ and methodology of operation considering both ‘Color grouping’ and ‘Option leveling.’