In this article, we review our studies concerning the design of novel functional polymers based on amino acids. Although an amino acid is the simplest optically active compound in the nature, its polymers, peptides, and proteins show a wide variety of functions such as electron transfer, information transfer, photo reactivity, and selective catalytic function, which cannot be imitated by synthetic compounds. It is expected to develop "artificial proteins" consisting of polymeric materials which show excellent functions, with exploring a precise molecular design based on amino acids.