The use of a new material is a hopeful strategy for breaking through the barrier of improving the product performance and/or the lowering of the product manufacturing cost. However, if the definite decision making method for selection of materials has not been established, use of a new material may not result in enhancement of the product performance and / or reduction of the product manufacturing cost. This paper proposes a methodology for decision making of a material used in machine structures from the standpoint of structural dynamics. First, purposes for use of new materials and evaluative parameters for decision making of material choice are described, and fundamental knowledge and theorems for decision making are established. Then, general decision making procedures for material choice are constructed. Finally, for model cases of purposes for use of new materials, detailed decision procedures are explained using also some numerical examples.