In this paper, the influence of the stamping effect is investigated in the performance analysis of a side structure. The analysis covers the performance evaluation such as crashworthiness and NVH. Stamping analyses are carried out for a center pillar, and then, numerical simulations are carried out in order to identify the stamping effect on the crashworthiness and the natural frequency. The result shows that the analysis considering the forming history leads to a different result from that without considering the stamping effect, which demonstrates that the design of auto-body should be carried out considering the stamping history for accurate assessment of various performances.