As environmental issues have been considered critical concerns of business, many corporations are rapidly adopting environmental management system(EMS) that conform ISO14001. But there has been little study on the relationship between EMS and corporate performance. Therefore, the active effort of firm's environmental management was not stimulated. In this point of view, this study examined whether or not the corporate adopting an ISO14001-certified EMS can function in the improvement of productivity, focusing on production process. The result of this study provides empirical evidence that there is a significant positive relation between the adoption of EMS and productivity. It is a commonly acceptable fact that the corporate adopting EMS experience a higher productivity than that of the corporate which don't adopt EMS, and that in the year which adopted EMS, corporate experience a higher productivity than that of last year when EMS was not adopted. These results may prove helpf