Sustainable society is a vision of the world common principle, Sustainable Development, and has three points of view such as Planet, People and Prosperity; which mean harmonization with the earth’s environment, improvement of the quality of human life and revitalization of social economy. To create artifacts that contribute to realization of the sustainable society, both maximization of the sum of their functional and monetary values and the minimization of their environmental impacts must be achieved simultaneously by the design methodology including an evaluation process based on the life cycle thinking. Here, the eco-efficiency is an effective tool for managing the progress of sustainable society through production and consumption of artifacts. On selection of materials in mechanical design, which influences on the performance, cost and environmental impact of artifacts, therefore, a rational method applying eco-efficiency indices has been developed to improve the sustainable design process. This paper presents a novel materials selection methodology synthesizing particular indices to express the sustainability of design objects, and describes its case studies to evaluate candidate materials for substituting materials of components.