The importance of environmental protection is frequently noted at present. Environmental problems, such as waste management, air pollution, and reduction of CO_2 emissions were discussed at the Kyoto Conference. As a result, the realization of the need for more products that perform better environmentally has been emphasized. Life Cycle Assessment (LCA) has been proposed as a method of controlling the environment relative to product manufacturing. This would be accomplished by designing and manufacturing products with better environmental performance. LCA is a technique for computing the environmental load of a product over the total product life cycle by performing inventory analysis of each life cycle process and summing up the results. However, since the LCA computes environmental load based on static database, it is difficult to consider flexible changes of a life cycle in its calculation. In this paper, we propose the new environmental load evaluation system, which can consider flexible changes of each life cycle process, by connecting external life cycle simulation systems to a LCA system.